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 A338438 #4 Oct 28 2020 09:29:19
%S A338438 1,1,0,3,4,15,6,168,64,171,130,44418,804,802750,2380,683595,5782144,
%T A338438 840363295,40410,24358246734,221953840,3114081516,5372831860,
%U A338438 62269802986834,25703183400,548547778815000,3028000483716,9604167089258628,30673543523224,13242158988496348746
%N A338438 a(n) = n! * [x^n] Product_{k=1..n, gcd(n,k) = 1} (1 + x^k/k!).
%t A338438 Table[n! SeriesCoefficient[Product[(1 + Boole[GCD[n, k] == 1] x^k/k!), {k, 1, n}], {x, 0, n}], {n, 0, 29}]
%Y A338438 Cf. A007837, A036998, A338436.
%K A338438 nonn
%O A338438 0,4
%A A338438 _Ilya Gutkovskiy_, Oct 27 2020