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 A320851 #4 Oct 22 2018 12:01:04 %S A320851 1,1,4,9,18,35,61,100,156,235,342,482,664,895,1185,1542,1977,2505, %T A320851 3134,3879,4757,5782,6968,8337,9909,11699,13732,16030,18615,21514, %U A320851 24755,28361,32362,36789,41673,47051,52953,59412,66466,74158,82525,91611,101454,112097 %N A320851 Number of 5-element subsets of [n] whose sum is a triangular number. %H A320851 Alois P. Heinz, <a href="/A320851/b320851.txt">Table of n, a(n) for n = 5..1000</a> %Y A320851 Column k=5 of A284249. %Y A320851 Cf. A000217. %K A320851 nonn %O A320851 5,3 %A A320851 _Alois P. Heinz_, Oct 22 2018