A015006 q-factorial numbers for q=7.

1, 1, 8, 456, 182400, 510902400, 10017774259200, 1375009641495014400, 1321109263548409835520000, 8885253784030448738183147520000, 418310711031156574478261944188764160000, 137856159231156714984163673320892478249861120000

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..40

Index entries for sequences related to factorial numbers

Formula

a(n) = Product_{k=1..n} (7^k-1)/(7-1).

a(0) = 1, a(n) = (7^n - 1)*a(n-1)/6. - Vincenzo Librandi, Oct 25 2012

Mathematica

RecurrenceTable[{a[1]==1, a[n]==((7^n - 1) * a[n-1])/6}, a, {n, 15}] (* Vincenzo Librandi, Oct 25 2012 *)
Table[QFactorial[n, 7], {n, 15}] (* Bruno Berselli, Aug 14 2013 *)

Prog

(Magma) [n le 1 select 1 else (7^n-1)*Self(n-1)/6: n in [1..15]]; // Vincenzo Librandi, Oct 25 2012

Crossrefs

Cf. A015001, A015002, A015004, A015005, A015007, A015008, A015009, A015011.

Column q=7 of A069777.

Sequence in context: A187049 A367707 A221157 * A279383 A054326 A203526

Adjacent sequences: A015003 A015004 A015005 * A015007 A015008 A015009

Keyword

nonn,easy

Author

Olivier Gérard

Extensions

a(0)=1 prepended by Alois P. Heinz, Sep 08 2021

Status

approved