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 A382979 #15 Apr 13 2025 13:39:43
%S A382979 1,-2,4,-20,78,-282,1048,-4014,15456,-59224,227646,-879694,3407730,
%T A382979 -13219372,51375286,-200021556,779870542,-3044448644,11898709560,
%U A382979 -46553635346,182315752476,-714619687038,2803342734160,-11005274516610,43233909672938,-169951684067602,668474115081988
%N A382979 a(n) = [(x*y)^n] Product_{k>=1} 1/(1 - x^k + y^k).
%H A382979 Vaclav Kotesovec, <a href="/A382979/b382979.txt">Table of n, a(n) for n = 0..200</a>
%F A382979 a(n) ~ (-1)^n * 4^n / (A100221 * sqrt(Pi*n)). - _Vaclav Kotesovec_, Apr 13 2025
%t A382979 a[n_]:=SeriesCoefficient[Product[1/(1-x^k+y^k),{k,1,n+5}],{x,0,n},{y,0,n}]; Table[a[n],{n,0,26}] (* _Vincenzo Librandi_, Apr 12 2025 *)
%o A382979 (Magma) nmax := 26; prec := 2*nmax + 10; Rx<x> := PowerSeriesRing(Rationals(), prec); Rxy<y> := PowerSeriesRing(Rx, prec); P := Rxy!1; for k in [1..prec] do P *:= 1/(1 - x^k + y^k); end for; seq := [Coefficient(Coefficient(P, n), n) : n in [0..nmax]]; print seq; // _Vincenzo Librandi_, Apr 12 2025
%Y A382979 Main diagonal of A382974.
%Y A382979 Cf. A322211, A100221.
%K A382979 sign
%O A382979 0,2
%A A382979 _Seiichi Manyama_, Apr 11 2025