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 A255879 #6 Jun 01 2020 11:49:34
%S A255879 1,3,4,6,10,15,16,18,21,28,36,45,46,48,51,55,66,78,91,105,106,108,111,
%T A255879 115,120,136,153,171,190,210,211,213,216,220,225,231,253,276,300,325,
%U A255879 351,378,379,381,384,388,393,399,406,435,465,496,528,561,595,630
%N A255879 Partial sums of A256188.
%H A255879 Reinhard Zumkeller, <a href="/A255879/b255879.txt">Table of n, a(n) for n = 1..10000</a>
%t A255879 Accumulate[Table[If[OddQ[Sqrt[8n+1]],Range[(Sqrt[8n+1]-1)/2],n],{n,50}]// Flatten] (* _Harvey P. Dale_, Jun 01 2020 *)
%o A255879 (Haskell)
%o A255879 a255879 n = a255879_list !! (n-1)
%o A255879 a255879_list = scanl1 (+) a256188_list
%Y A255879 Cf. A256188, A255437.
%K A255879 nonn
%O A255879 1,2
%A A255879 _Reinhard Zumkeller_, Mar 26 2015