1
$\begingroup$

This question already has an answer here:

Triangle numbers are $0,1,3,6,10...$ And square numbers are $0,1,4,9,16...$ $N$'th triangle no. = $N(N+1)/2$ $N$'th square no. = $N\cdot N$

So I was wondering are there any numbers which are in both these lists apart from $0,1$??

I found one using trial and error that is $36$ which is the $8$'th triangular number and $6$'th square number. Are there more? What is the algebraic method to calculate them?? thanks in advance.

$\endgroup$

marked as duplicate by Stella Biderman, Lord Shark the Unknown, Nosrati, Chris Godsil, Shailesh Dec 17 '17 at 3:13

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.