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A338880 Product of the nonzero digits of (n written in base 7). 1
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 (list; graph; refs; listen; history; text; internal format)
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 + 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, 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

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Last modified June 13 16:45 EDT 2021. Contains 345008 sequences. (Running on oeis4.)