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q-factorial numbers for q=-7.
1

%I #14 Sep 08 2022 08:44:39

%S 1,-6,-258,77400,162617400,-2391451484400,-246183190158589200,

%T 177399606828279377520000,894839274162813664365761520000,

%U -31596243236160097777438406008857120000

%N q-factorial numbers for q=-7.

%H Vincenzo Librandi, <a href="/A015020/b015020.txt">Table of n, a(n) for n = 1..40</a>

%H <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>

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

%F a(1) = 1, a(n) = ((-7)^n - 1)*a(n-1)/(-8). - _Vincenzo Librandi_, Oct 26 2012

%t RecurrenceTable[{a[1]==1, a[n]==(((-7)^n - 1) * a[n-1])/(-8)}, a, {n, 15}] (* _Vincenzo Librandi_, Oct 26 2012 *)

%o (Magma) [n le 1 select 1 else ((-7)^n - 1)*Self(n-1)/(-8): n in [1..13]]; // _Vincenzo Librandi_, Oct 26 2012

%K sign,easy

%O 1,2

%A _Olivier GĂ©rard_