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 A338854 Product of the nonzero digits of (n written in base 4). 1
 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, 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, 1, 2, 3, 1, 1, 2, 3, 2, 2, 4, 6, 3, 3, 6, 9, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2 + 3*x^3) * A(x^4). a(n) = 2^A160382(n) * 3^A160383(n). MATHEMATICA Table[Times @@ DeleteCases[IntegerDigits[n, 4], 0], {n, 0, 80}] 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] PROG (PARI) a(n) = vecprod(select(x->x, digits(n, 4))); \\ Michel Marcus, Nov 12 2020 CROSSREFS Cf. A007090, A051801, A117592, A160382, A160383, A309954. Sequence in context: A190593 A276336 A212811 * A330957 A327192 A157813 Adjacent sequences:  A338851 A338852 A338853 * A338855 A338856 A338857 KEYWORD nonn,base AUTHOR Ilya Gutkovskiy, Nov 12 2020 STATUS approved

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Last modified August 5 18:00 EDT 2021. Contains 346488 sequences. (Running on oeis4.)