This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A015006 #31 Jul 06 2025 10:11:37
%S A015006 1,1,8,456,182400,510902400,10017774259200,1375009641495014400,
%T A015006 1321109263548409835520000,8885253784030448738183147520000,
%U A015006 418310711031156574478261944188764160000,137856159231156714984163673320892478249861120000
%N A015006 q-factorial numbers for q=7.
%H A015006 Vincenzo Librandi, <a href="/A015006/b015006.txt">Table of n, a(n) for n = 0..40</a>
%H A015006 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A015006 a(n) = Product_{k=1..n} (7^k-1)/(7-1).
%F A015006 a(0) = 1, a(n) = (7^n - 1)*a(n-1)/6. - _Vincenzo Librandi_, Oct 25 2012
%F A015006 From _Amiram Eldar_, Jul 05 2025: (Start)
%F A015006 a(n) = Product_{k=1..n} A023000(k).
%F A015006 a(n) ~ c * 7^(n*(n+1)/2)/6^n, where c = A132035. (End)
%t A015006 RecurrenceTable[{a[1]==1, a[n]==((7^n - 1) * a[n-1])/6}, a, {n, 15}] (* _Vincenzo Librandi_, Oct 25 2012 *)
%t A015006 Table[QFactorial[n, 7], {n, 15}] (* _Bruno Berselli_, Aug 14 2013 *)
%o A015006 (Magma) [n le 1 select 1 else (7^n-1)*Self(n-1)/6: n in [1..15]]; // _Vincenzo Librandi_, Oct 25 2012
%Y A015006 Cf. A015001, A015002, A015004, A015005, A015007, A015008, A015009, A015011.
%Y A015006 Column q=7 of A069777.
%Y A015006 Cf. A023000, A132035.
%K A015006 nonn,easy
%O A015006 0,3
%A A015006 _Olivier Gérard_
%E A015006 a(0)=1 prepended by _Alois P. Heinz_, Sep 08 2021