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 A039826 #26 Jan 31 2024 16:56:39
%S A039826 1,2,3,7,15,36,87,217,549,1423,3735,9911,26513,71581,194681,532481,
%T A039826 1464029,4045117,11225159,31268577,87404465,245101771,689323849,
%U A039826 1943817227,5494808425,15568077235,44200775239,125739619467,358347118257,1022994133467,2925044957099,8376049588815,24018964753341
%N A039826 Largest coefficient in expansion of Product_{i=1..n} (1 + q^i + q^(2i)).
%H A039826 Ray Chandler, <a href="/A039826/b039826.txt">Table of n, a(n) for n = 1..2106</a> (terms < 10^1000)
%H A039826 Steven R. Finch, <a href="/A000980/a000980.pdf">Signum equations and extremal coefficients</a>, February 7, 2009. [Cached copy, with permission of the author]
%F A039826 a(n) ~ 3^(n+1) / (2*sqrt(Pi)*n^(3/2)). - _Vaclav Kotesovec_, Jul 11 2018
%t A039826 nmax = 28; d = {1}; a1 = {};
%t A039826 Do[
%t A039826 n0s = Table[0, {n}];
%t A039826 d = Join[d, n0s, n0s] + Join[n0s, d, n0s] + Join[n0s, n0s, d];
%t A039826 AppendTo[a1, Last[Union[d]]];
%t A039826 , {n, nmax}];
%t A039826 a1 (* _Ray Chandler_, Mar 26 2014 *)
%o A039826 (PARI) a(n)=vecmax(Vec(prod(k=1,n,1+x^k+x^(2*k))));
%o A039826 vector(50,n,a(n)) \\ _Joerg Arndt_, Jan 31 2024
%Y A039826 Cf. A039827.
%K A039826 nonn
%O A039826 1,2
%A A039826 _Olivier Gérard_