A015019 q-factorial numbers for q=-6.

1, -5, -155, 28675, 31857925, -212333070125, -8491411807368875, 2037471806119124711875, 2933289072587326393069793125, -25337824341236140066496699758578125, -1313212585969062194023540996089250607796875

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..50

Index entries for sequences related to factorial numbers

Formula

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

a(1) = 1, a(n) = ((-6)^n - 1)*a(n-1)/(-7). - Vincenzo Librandi, Oct 26 2012

Mathematica

RecurrenceTable[{a[1]==1, a[n]==(((-6)^n - 1) * a[n-1])/(-7)}, a, {n, 15}] (* Vincenzo Librandi, Oct 26 2012 *)

Prog

(Magma) [n le 1 select 1 else ((-6)^n - 1)*Self(n-1)/(-7): n in [1..18]]; // Vincenzo Librandi, Oct 26 2012

Crossrefs

Sequence in context: A108535 A265123 A237527 * A225165 A151577 A032391

Adjacent sequences: A015016 A015017 A015018 * A015020 A015021 A015022

Keyword

sign,easy

Author

Olivier Gérard

Status

approved