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A015015 q-factorial numbers for q=-3. 1
1, -2, -14, 280, 17080, -3108560, -1700382320, 2788627004800, 13722833490620800, -202576467988544249600, -8971504037808659182035200, 1191954026463258458925196672000, 475090227821752019816863814722432000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..60

Index entries for sequences related to factorial numbers

FORMULA

a(n) = product_{k=1..n} ((-3)^k - 1)/(-3 - 1).

a(1) = 1, a(n) = ((-3)^n - 1)*a(n-1)/(-4). - Vincenzo Librandi, Oct 26 2012

MATHEMATICA

RecurrenceTable[{a[1]==1, a[n]==(((-3)^n - 1) * a[n-1])/(-4)}, a, {n, 18}] (* Vincenzo Librandi, Oct 26 2012 *)

PROG

(MAGMA) [n le 1 select 1 else ((-3)^n - 1)*Self(n-1)/(-4): n in [1..18]]; // Vincenzo Librandi, Oct 26 2012

CROSSREFS

Sequence in context: A018803 A217474 A132695 * A128087 A139225 A277035

Adjacent sequences:  A015012 A015013 A015014 * A015016 A015017 A015018

KEYWORD

sign,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified October 23 23:51 EDT 2019. Contains 328379 sequences. (Running on oeis4.)