A015007 - OEIS

%I #24 Sep 08 2022 08:44:39

%S 1,1,9,657,384345,1799118945,67375205371305,20185139902805378865,

%T 48378633136349277767794425,927610024989668734297857360967425,

%U 142287668466497494704440569679875994730825,174605966461872393482359052970987514818406771638225

%N q-factorial numbers for q=8.

%H Vincenzo Librandi, <a href="/A015007/b015007.txt">Table of n, a(n) for n = 0..40</a>

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

%F a(n) = Product_{k=1..n} ((q^k - 1) / (q - 1)), with q=8.

%F a(0) = 1, a(n) = (8^n-1)*a(n-1)/7. - _Vincenzo Librandi_, Oct 26 2012

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

%t Table[QFactorial[n, 8], {n, 15}] (* _Bruno Berselli_, Aug 14 2013 *)

%o (Magma) [n le 1 select 1 else (8^n-1)*Self(n-1)/7: n in [1..15]]; // _Vincenzo Librandi_, Oct 26 2012

%Y Cf. A015001, A015002, A015004, A015005, A015006, A015008, A015009, A015011.

%Y Column q=8 of A069777.

%K nonn,easy

%O 0,3

%A _Olivier Gérard_

%E a(0)=1 prepended by _Alois P. Heinz_, Sep 08 2021