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 A015026 #30 Aug 10 2025 02:38:54
%S A015026 1,1,-10,-1110,1354200,18174718200,-2683133647866000,
%T A015026 -4357223907912681246000,77834136400782124140797040000,
%U A015026 15294068523753116384387488625702640000,-33057395763506647102922925284376653918412000000,-785971734280677729025139143429963192709390305509012000000
%N A015026 q-factorial numbers for q=-11.
%H A015026 Vincenzo Librandi, <a href="/A015026/b015026.txt">Table of n, a(n) for n = 0..40</a>
%H A015026 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A015026 a(n) = Product_{k=1..n} ((-11)^k - 1) / (-11 - 1).
%F A015026 a(1) = 1, a(n) = ((-11)^n - 1) * a(n-1)/(-12). - _Vincenzo Librandi_, Oct 26 2012
%F A015026 a(n) ~ (-1)^floor(n/2) * c * 11^(n*(n+1)/2) / 12^n, where c = Product_{k>=1} (1 - 1/(-11)^k) = 1.08263836756981274767... . - _Amiram Eldar_, Aug 10 2025
%t A015026 RecurrenceTable[{a[1]==1, a[n]==(((-11)^n - 1) a[n-1])/(-12)}, a, {n, 15}] (* _Vincenzo Librandi_, Oct 26 2012 *)
%o A015026 (Magma) [n le 1 select 1 else ((-11)^n - 1)*Self(n-1)/(-12): n in [1..13]]; // _Vincenzo Librandi_, Oct 26 2012
%Y A015026 Column k=11 of A384454.
%Y A015026 Cf. A015011.
%K A015026 sign,easy
%O A015026 0,3
%A A015026 _Olivier Gérard_
%E A015026 a(0)=1 prepended by _Seiichi Manyama_, May 30 2025