Voozh

A338863

Product of the nonzero digits of (n written in base 6).

1, 1, 2, 3, 4, 5, 1, 1, 2, 3, 4, 5, 2, 2, 4, 6, 8, 10, 3, 3, 6, 9, 12, 15, 4, 4, 8, 12, 16, 20, 5, 5, 10, 15, 20, 25, 1, 1, 2, 3, 4, 5, 1, 1, 2, 3, 4, 5, 2, 2, 4, 6, 8, 10, 3, 3, 6, 9, 12, 15, 4, 4, 8, 12, 16, 20, 5, 5, 10, 15, 20, 25, 2, 2, 4, 6, 8, 10, 2, 2, 4

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..80.

FORMULA

G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2 + 3*x^3 + 4*x^4 + 5*x^5) * A(x^6).

MATHEMATICA

Table[Times @@ DeleteCases[IntegerDigits[n, 6], 0], {n, 0, 80}]

nmax = 80; A[_] = 1; Do[A[x_] = (1 + x + 2 x^2 + 3 x^3 + 4 x^4 + 5 x^5) A[x^6] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]

PROG

(PARI) a(n) = vecprod(select(x->x, digits(n, 6))); \\ Michel Marcus, Nov 13 2020