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 A328286 #14 Mar 06 2022 09:45:46
%S A328286 1,2,5,21,114,780,6390,61110,667800,8210160,112152600,1685237400,
%T A328286 27624920400,490572482400,9381882510000,192238348302000,
%U A328286 4201639474032000,97572286427616000,2399151995223984000,62268748888378032000,1701213856860117600000
%N A328286 Expansion of e.g.f. -log(1 - x - x^2/2).
%F A328286 a(n) = (n - 1)! * ((1 - sqrt(3))^n + (1 + sqrt(3))^n) / 2^n.
%F A328286 D-finite with recurrence +2*a(n) +2*(-n+1)*a(n-1) -(n-1)*(n-2)*a(n-2)=0. - _R. J. Mathar_, Aug 20 2021
%p A328286 b:= proc(n) b(n):= n! * (<<1|1>, <1/2|0>>^n)[1, 1] end:
%p A328286 a:= proc(n) option remember; `if`(n=0, 0, b(n)-add(
%p A328286 binomial(n, j)*j*b(n-j)*a(j), j=1..n-1)/n)
%p A328286 end:
%p A328286 seq(a(n), n=1..25); # _Alois P. Heinz_, Oct 11 2019
%t A328286 nmax = 21; CoefficientList[Series[-Log[1 - x - x^2/2], {x, 0, nmax}], x] Range[0, nmax]! // Rest
%t A328286 FullSimplify[Table[(n - 1)! ((1 - Sqrt[3])^n + (1 + Sqrt[3])^n)/2^n, {n, 1, 21}]]
%o A328286 (PARI) my(x='x+O('x^25)); Vec(serlaplace(-log(1 - x - x^2/2))) \\ _Michel Marcus_, Oct 11 2019
%Y A328286 Cf. A009014, A039647, A080040, A080599 (exponential transform).
%K A328286 nonn
%O A328286 1,2
%A A328286 _Ilya Gutkovskiy_, Oct 11 2019