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 A320849 #4 Oct 22 2018 11:56:36 %S A320849 1,1,3,5,8,12,16,22,29,37,46,57,69,82,97,114,131,150,171,194,219,245, %T A320849 273,302,334,368,404,441,480,522,567,613,660,710,762,818,876,936,997, %U A320849 1061,1127,1196,1268,1342,1419,1498,1580,1664,1751,1841,1934,2029,2127 %N A320849 Number of 3-element subsets of [n] whose sum is a triangular number. %H A320849 Alois P. Heinz, <a href="/A320849/b320849.txt">Table of n, a(n) for n = 3..10000</a> %Y A320849 Column k=3 of A284249. %Y A320849 Cf. A000217. %K A320849 nonn %O A320849 3,3 %A A320849 _Alois P. Heinz_, Oct 22 2018