Multiples of triangular numbers












0












$begingroup$


I know that $;2T_2=T_3;$ is a triangular number.

Can anyone suggest me other triangular numbers whose two multiple is again a triangular number?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
    $endgroup$
    – Matti P.
    Jan 22 at 8:41








  • 4




    $begingroup$
    See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:42






  • 1




    $begingroup$
    Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
    $endgroup$
    – José Carlos Santos
    Jan 22 at 8:43










  • $begingroup$
    Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
    $endgroup$
    – Matti P.
    Jan 22 at 8:44












  • $begingroup$
    See also oeis.org/A029549
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:44
















0












$begingroup$


I know that $;2T_2=T_3;$ is a triangular number.

Can anyone suggest me other triangular numbers whose two multiple is again a triangular number?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
    $endgroup$
    – Matti P.
    Jan 22 at 8:41








  • 4




    $begingroup$
    See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:42






  • 1




    $begingroup$
    Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
    $endgroup$
    – José Carlos Santos
    Jan 22 at 8:43










  • $begingroup$
    Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
    $endgroup$
    – Matti P.
    Jan 22 at 8:44












  • $begingroup$
    See also oeis.org/A029549
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:44














0












0








0





$begingroup$


I know that $;2T_2=T_3;$ is a triangular number.

Can anyone suggest me other triangular numbers whose two multiple is again a triangular number?










share|cite|improve this question











$endgroup$




I know that $;2T_2=T_3;$ is a triangular number.

Can anyone suggest me other triangular numbers whose two multiple is again a triangular number?







real-numbers






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 22 at 9:03









user376343

3,9234829




3,9234829










asked Jan 22 at 8:35









AnuAnu

1




1












  • $begingroup$
    Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
    $endgroup$
    – Matti P.
    Jan 22 at 8:41








  • 4




    $begingroup$
    See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:42






  • 1




    $begingroup$
    Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
    $endgroup$
    – José Carlos Santos
    Jan 22 at 8:43










  • $begingroup$
    Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
    $endgroup$
    – Matti P.
    Jan 22 at 8:44












  • $begingroup$
    See also oeis.org/A029549
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:44


















  • $begingroup$
    Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
    $endgroup$
    – Matti P.
    Jan 22 at 8:41








  • 4




    $begingroup$
    See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:42






  • 1




    $begingroup$
    Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
    $endgroup$
    – José Carlos Santos
    Jan 22 at 8:43










  • $begingroup$
    Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
    $endgroup$
    – Matti P.
    Jan 22 at 8:44












  • $begingroup$
    See also oeis.org/A029549
    $endgroup$
    – Mark Bennet
    Jan 22 at 8:44
















$begingroup$
Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
$endgroup$
– Matti P.
Jan 22 at 8:41






$begingroup$
Hint: Triangular numbers in general are of the form $$ T_n = frac{n(n+1)}{2} $$ So if you have $2T_r = T_s$ for some pair $(r,s)$, what are their possible values?
$endgroup$
– Matti P.
Jan 22 at 8:41






4




4




$begingroup$
See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
$endgroup$
– Mark Bennet
Jan 22 at 8:42




$begingroup$
See this near duplicate math.stackexchange.com/questions/2075913/…. You get a Pell equation.
$endgroup$
– Mark Bennet
Jan 22 at 8:42




1




1




$begingroup$
Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
$endgroup$
– José Carlos Santos
Jan 22 at 8:43




$begingroup$
Welcome to MSE. You should choose your tags carefully. What has this to do with real-numbers?
$endgroup$
– José Carlos Santos
Jan 22 at 8:43












$begingroup$
Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
$endgroup$
– Matti P.
Jan 22 at 8:44






$begingroup$
Another pair is $(14,20)$. And $(84,119)$, $(494,696)$ ...
$endgroup$
– Matti P.
Jan 22 at 8:44














$begingroup$
See also oeis.org/A029549
$endgroup$
– Mark Bennet
Jan 22 at 8:44




$begingroup$
See also oeis.org/A029549
$endgroup$
– Mark Bennet
Jan 22 at 8:44










0






active

oldest

votes











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3082887%2fmultiples-of-triangular-numbers%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3082887%2fmultiples-of-triangular-numbers%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

'app-layout' is not a known element: how to share Component with different Modules

android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

WPF add header to Image with URL pettitions [duplicate]