A338880 Product of the nonzero digits of (n written in base 7).

1, 1, 2, 3, 4, 5, 6, 1, 1, 2, 3, 4, 5, 6, 2, 2, 4, 6, 8, 10, 12, 3, 3, 6, 9, 12, 15, 18, 4, 4, 8, 12, 16, 20, 24, 5, 5, 10, 15, 20, 25, 30, 6, 6, 12, 18, 24, 30, 36, 1, 1, 2, 3, 4, 5, 6, 1, 1, 2, 3, 4, 5, 6, 2, 2, 4, 6, 8, 10, 12, 3, 3, 6, 9, 12, 15, 18, 4, 4, 8, 12

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..9603

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) * A(x^7).

Mathematica

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

Prog

(PARI) a(n) = vecprod(select(x->x, digits(n, 7))); \\ Michel Marcus, Nov 14 2020

Crossrefs

Cf. A007093, A051801, A053828, A117592, A309958.

Sequence in context: A255827 A277545 A190596 * A053842 A010885 A338480

Adjacent sequences: A338877 A338878 A338879 * A338881 A338882 A338883

Keyword

nonn,base

Author

Ilya Gutkovskiy, Nov 13 2020

Status

approved