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 A015001 #47 Jul 06 2025 10:11:05
%S A015001 1,1,4,52,2080,251680,91611520,100131391360,328430963660800,
%T A015001 3232089113385932800,95424198983606279987200,
%U A015001 8452007576574959037306265600,2245867453247498115393020895232000,1790317944898228845164815929864036352000
%N A015001 q-factorial numbers for q=3.
%C A015001 a(n) is the number of maximal chains in the lattice of subspaces of an n-dimensional vector space over GF(3). - _Geoffrey Critzer_, Sep 07 2022
%H A015001 Vincenzo Librandi, <a href="/A015001/b015001.txt">Table of n, a(n) for n = 0..50</a>
%H A015001 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A015001 a(n) = Product_{k=1..n} (q^k - 1) / (q - 1).
%F A015001 a(0) = 1, a(n) = (3^n - 1)*a(n-1)/2. - _Vincenzo Librandi_, Oct 27 2012
%F A015001 a(n) = (Product_{i=0..n-1} (q^n-q^i))/((q-1)^n*q^binomial(n,2)) = A053290(n)/(A000079(n)*A047656(n)). - _Geoffrey Critzer_, Sep 07 2022
%F A015001 From _Amiram Eldar_, Jul 05 2025: (Start)
%F A015001 a(n) = Product_{k=1..n} A003462(k).
%F A015001 a(n) ~ c * 3^(n*(n+1)/2)/2^n, where c = A100220. (End)
%t A015001 RecurrenceTable[{a[1]==1, a[n]==((3^n - 1) * a[n-1])/2}, a, {n,15}] (* _Vincenzo Librandi_, Oct 27 2012 *)
%t A015001 Table[QFactorial[n, 3], {n, 15}] (* _Bruno Berselli_, Aug 14 2013 *)
%o A015001 (Magma) [n le 1 select 1 else (3^n-1)*Self(n-1)/2: n in [1..15]]; // _Vincenzo Librandi_, Oct 22 2012
%Y A015001 Cf. A015002, A015004, A015005, A015006, A015007, A015008, A015009, A015011.
%Y A015001 Column q=3 of A069777.
%Y A015001 Cf. A000079, A003462, A047656, A053290, A100220.
%K A015001 nonn,easy
%O A015001 0,3
%A A015001 _Olivier Gérard_
%E A015001 a(0)=1 prepended by _Alois P. Heinz_, Sep 08 2021