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 A039909 #24 Jan 05 2023 18:30:05
%S A039909 1,1,2,5,20,101,573,3836,29228,250749,2409581,25380120,294625748,
%T A039909 3727542188,50626553988,738680521142,11501573822788,190418421447330,
%U A039909 3344822488498265,61995904304519920,1212867413232346644,24965661442811799655,538134522243713149122
%N A039909 Largest coefficient in expansion of Product_{i=1..n} (1-q^1+q^2-...+(-q)^i).
%H A039909 Seiichi Manyama, <a href="/A039909/b039909.txt">Table of n, a(n) for n = 0..200</a>
%F A039909 Conjecture: a(n) ~ 6 * n^n / exp(n). - _Vaclav Kotesovec_, Jan 05 2023
%o A039909 (Magma) PS<q>:=PowerSeriesRing(Integers()); [ Max(Coefficients(&*[&+[ (-q)^i: i in [0..j] ]: j in [0..n] ])): n in [1..20] ]; // _Klaus Brockhaus_, Jan 18 2011
%o A039909 (PARI) a(n) = vecmax(Vec(prod(j=1, n, sum(k=0, j, (-x)^k)))); \\ _Seiichi Manyama_, Jan 05 2023
%Y A039909 Cf. A000140, A039828, A039830.
%K A039909 nonn
%O A039909 0,3
%A A039909 _Olivier Gérard_
%E A039909 a(0)=1 prepended by _Seiichi Manyama_, Jan 05 2023