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 A288631 #10 Feb 16 2025 08:33:47
%S A288631 2,6,10,15,19,28,31,35,44,56,60,69,85,92,96,105,110,121,141,145,146,
%T A288631 154,170,182,195,205,209,218,231,234,259,280,286,290,295,299,315,340,
%U A288631 344,376,386,390,399,408,415,425,440,476,489,507,511,520,525,536,561,570,589,597,646,651,655,664,670,680
%N A288631 Numbers that are the sum of two nonzero square pyramidal numbers (A000330).
%H A288631 Robert Israel, <a href="/A288631/b288631.txt">Table of n, a(n) for n = 1..10000</a>
%H A288631 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquarePyramidalNumber.html">Square Pyramidal Number</a>
%H A288631 <a href="/index/Ps#pyramidal_numbers">Index to sequences related to pyramidal numbers</a>
%p A288631 M:= 20: # to get all terms <= A000330(M)
%p A288631 sqp:= [seq(k*(k+1)*(2*k+1)/6, k=1..M)]:
%p A288631 sort(convert(select(`<=`, {seq(seq(sqp[i]+sqp[j], j=1..i),i=1..M-1)},sqp[M]),list)); # _Robert Israel_, Jun 12 2017
%t A288631 nmax = 700; f[x_] := Sum[x^(k (k + 1) (2 k + 1)/6), {k, 1, 20}]^2; Exponent[#, x] & /@ List @@ Normal[Series[f[x], {x, 0, nmax}]]
%Y A288631 Cf. A000330, A000404, A020756, A051533, A102795.
%K A288631 nonn
%O A288631 1,1
%A A288631 _Ilya Gutkovskiy_, Jun 12 2017