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 A357931 #13 Nov 01 2023 04:12:57
%S A357931 1,1,1,1,2,4,7,13,27,57,120,262,593,1361,3171,7559,18356,45186,112927,
%T A357931 286689,737641,1921639,5070154,13540352,36566737,99830013,275459693,
%U A357931 767798853,2160953618,6139721116,17604534427,50924095081,148570523479,437071675997
%N A357931 a(n) = Sum_{k=0..floor(n/3)} |Stirling1(n - 2*k,n - 3*k)|.
%F A357931 G.f.: Sum_{k>=0} x^k * Product_{j=0..k-1} (1 + j * x^2).
%t A357931 Table[Sum[Abs[StirlingS1[n-2k,n-3k]],{k,0,Floor[n/3]}],{n,0,40}] (* _Harvey P. Dale_, Nov 01 2023 *)
%o A357931 (PARI) a(n) = sum(k=0, n\3, abs(stirling(n-2*k, n-3*k, 1)));
%o A357931 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, x^k*prod(j=0, k-1, 1+j*x^2)))
%Y A357931 Cf. A124380, A357932, A357933.
%Y A357931 Cf. A353223, A357901, A357925.
%K A357931 nonn
%O A357931 0,5
%A A357931 _Seiichi Manyama_, Oct 21 2022