A015023 q-factorial numbers for q=-9.

1, -8, -584, 383104, 2262229120, -120223904353280, -57502732780460764160, 247530403723531598578155520, 9589835030046843645163231485460480, -3343768718134086569119429099709242848051200

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..40

Index entries for sequences related to factorial numbers

Formula

prod_{k=1}^{k=n} {(q^k - 1) / (q - 1)}

a(1) = 1, a(n) = (((-9)^n - 1) * a(n-1))/(-10). - Vincenzo Librandi, Oct 26 2012

Mathematica

RecurrenceTable[{a[1]==1, a[n]==(((-9)^n - 1) * a[n-1])/(-10)}, a, {n, 15}] (* Vincenzo Librandi, Oct 26 2012 *)

Prog

(Magma) I:=[1]; [n le 1 select I[n] else (((-9)^n - 1) * Self(n-1))/(-10): n in [1..13]]; // Vincenzo Librandi, Oct 26 2012

Crossrefs

Sequence in context: A326552 A303933 A188780 * A225168 A332158 A269508

Adjacent sequences: A015020 A015021 A015022 * A015024 A015025 A015026

Keyword

sign,easy

Author

Olivier Gérard

Status

approved