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 A015009 #31 Jul 06 2025 10:12:30
%S A015009 1,1,11,1221,1356531,15072415941,1674711207620451,
%T A015009 1860790044610366931061,20675444733360738721748118771,
%U A015009 2297271634742810443154153338805764581,2552524038347870310755413660544832496799359491,28361378203581611893021499527080870668821235178133404501
%N A015009 q-factorial numbers for q=10.
%H A015009 Vincenzo Librandi, <a href="/A015009/b015009.txt">Table of n, a(n) for n = 0..40</a>
%H A015009 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A015009 a(n) = Product_{k=1..n} (q^k - 1)/(q - 1) with q=10.
%F A015009 a(0) = 1, a(n) = (10^n - 1)*a(n-1)/9. - _Vincenzo Librandi_, Oct 26 2012
%F A015009 From _Amiram Eldar_, Jul 05 2025: (Start)
%F A015009 a(n) = Product_{k=1..n} A002275(k).
%F A015009 a(n) ~ c * 10^(n*(n+1)/2)/9^n, where c = A132038. (End)
%t A015009 RecurrenceTable[{a[1]==1, a[n]==((10^n-1) * a[n-1])/9}, a, {n, 15}] (* _Vincenzo Librandi_, Oct 26 2012 *)
%t A015009 Table[QFactorial[n, 10], {n, 15}] (* _Bruno Berselli_, Aug 14 2013 *)
%o A015009 (Magma) [n le 1 select 1 else (10^n-1)*Self(n-1)/9: n in [1..15]]; // _Vincenzo Librandi_, Oct 26 2012
%Y A015009 Cf. A015001, A015002, A015004, A015005, A015006, A015007, A015008, A015011.
%Y A015009 Column q=10 of A069777.
%Y A015009 Cf. A002275, A132038.
%K A015009 nonn,easy
%O A015009 0,3
%A A015009 _Olivier Gérard_
%E A015009 a(0)=1 prepended by _Alois P. Heinz_, Sep 08 2021