This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A053612 #14 May 18 2015 08:06:59 %S A053612 1,10,13,645 %N A053612 Numbers such that 1+2+3...+a(n) = 1+4+9+...+r^2, for some r. %D A053612 Joe Roberts, Lure of the Integers, page 245 (entry for 645). %H A053612 R. Finkelstein, H. London, <a href="http://dx.doi.org/10.1016/0022-314X(72)90036-4">On triangular numbers which are sums of consecutive squares</a>, J. Number Theory 4 (1972), 455-462. %e A053612 1^2 + 2^2 + 3^2 + 4^2 + 5^2 = 1 + 2 + 3 + ... + 10, so 10 is in the sequence. %Y A053612 Cf. A039596, A053611. %K A053612 fini,full,nonn %O A053612 1,2 %A A053612 _Jud McCranie_, Mar 19 2000