A338881 Product of the nonzero digits of (n written in base 8).

1, 1, 2, 3, 4, 5, 6, 7, 1, 1, 2, 3, 4, 5, 6, 7, 2, 2, 4, 6, 8, 10, 12, 14, 3, 3, 6, 9, 12, 15, 18, 21, 4, 4, 8, 12, 16, 20, 24, 28, 5, 5, 10, 15, 20, 25, 30, 35, 6, 6, 12, 18, 24, 30, 36, 42, 7, 7, 14, 21, 28, 35, 42, 49, 1, 1, 2, 3, 4, 5, 6, 7, 1, 1, 2, 3, 4, 5, 6, 7, 2

Offset: 0

Author

Ilya Gutkovskiy, Nov 13 2020

Keywords

• nonn
• base

Crossrefs

Cf. A007094, A051801, A117592, A309959.

Programs

Mathematica

Table[Times @@ DeleteCases[IntegerDigits[n, 8], 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 + 6 x^6 + 7 x^7) A[x^8] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]

PARI

a(n) = vecprod(select(x->x, digits(n, 8))); \\ Michel Marcus, Nov 14 2020

Formula

G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2 + 3*x^3 + 4*x^4 + 5*x^5 + 6*x^6 + 7*x^7) * A(x^8).