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 A320855 #4 Oct 22 2018 12:03:18 %S A320855 1,1,6,21,64,174,419,930,1921,3741,6933,12303,21044,34839,56044,87885, %T A320855 134682,202181,297873,431423,615166,864673,1199421,1643537,2226716, %U A320855 2985188,3962845,5212562,6797615,8793297,11288719,14388852,18216738,22915930,28653268 %N A320855 Number of 9-element subsets of [n] whose sum is a triangular number. %H A320855 Alois P. Heinz, <a href="/A320855/b320855.txt">Table of n, a(n) for n = 9..1000</a> %Y A320855 Column k=9 of A284249. %Y A320855 Cf. A000217. %K A320855 nonn %O A320855 9,3 %A A320855 _Alois P. Heinz_, Oct 22 2018