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 A338854 #6 Nov 13 2020 14:22:33
%S A338854 1,1,2,3,1,1,2,3,2,2,4,6,3,3,6,9,1,1,2,3,1,1,2,3,2,2,4,6,3,3,6,9,2,2,
%T A338854 4,6,2,2,4,6,4,4,8,12,6,6,12,18,3,3,6,9,3,3,6,9,6,6,12,18,9,9,18,27,1,
%U A338854 1,2,3,1,1,2,3,2,2,4,6,3,3,6,9,1
%N A338854 Product of the nonzero digits of (n written in base 4).
%F A338854 G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2 + 3*x^3) * A(x^4).
%F A338854 a(n) = 2^A160382(n) * 3^A160383(n).
%t A338854 Table[Times @@ DeleteCases[IntegerDigits[n, 4], 0], {n, 0, 80}]
%t A338854 nmax = 80; A[_] = 1; Do[A[x_] = (1 + x + 2 x^2 + 3 x^3) A[x^4] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%o A338854 (PARI) a(n) = vecprod(select(x->x, digits(n, 4))); \\ _Michel Marcus_, Nov 12 2020
%Y A338854 Cf. A007090, A051801, A117592, A160382, A160383, A309954.
%K A338854 nonn,base
%O A338854 0,3
%A A338854 _Ilya Gutkovskiy_, Nov 12 2020