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 A015027 #33 Aug 10 2025 02:38:37
%S A015027 1,1,-11,-1463,2333485,44665236385,-10259202810507035,
%T A015027 -28277368892180867021255,935288538953861649874525071325,
%U A015027 371221802129246962654056875248358359825,-1768082733073463162105209099485375242162416580075,-101053866980328304416804100016021966697144304636338865493975
%N A015027 q-factorial numbers for q=-12.
%H A015027 Vincenzo Librandi, <a href="/A015027/b015027.txt">Table of n, a(n) for n = 0..40</a>
%H A015027 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A015027 a(n) = Product_{k=1..n} (q^k - 1) / (q - 1) for q=-12.
%F A015027 a(0) = 1, a(n) = ((-12)^n -1)*a(n-1)/(-13). - _Vincenzo Librandi_, Oct 26 2012
%F A015027 a(n) ~ (-1)^floor(n/2) * c * 12^(n*(n+1)/2) / 13^n, where c = Product_{k>=1} (1 - 1/(-12)^k) = 1.07638484220489190916... . - _Amiram Eldar_, Aug 10 2025
%t A015027 RecurrenceTable[{a[1]==1, a[n]==(((-12)^n - 1) * a[n-1])/(-13)}, a, {n, 15}] (* _Vincenzo Librandi_, Oct 26 2012 *)
%o A015027 (Magma) [1] cat [n le 1 select 1 else ((-12)^n - 1)*Self(n-1)/(-13): n in [1..13]]; // _Vincenzo Librandi_, Oct 26 2012
%Y A015027 Column k=12 of A384454.
%K A015027 sign,easy
%O A015027 0,3
%A A015027 _Olivier Gérard_
%E A015027 a(0)=1 prepended by _Seiichi Manyama_, May 31 2025