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 A275706 #65 Feb 16 2025 08:33:36
%S A275706 1,1,2,1,-40,135,-860,20145,-137100,-6726225,-212460900,-3642898575,
%T A275706 654642826500,-26505894416625,3335048243533500,-1368325090374591375,
%U A275706 133951676745003682500,123266968248328746879375,63057521158814641016317500,17732380504905960076345280625
%N A275706 a(n) = Re([n]_{1+i}!), where [n]_q! is the q-factorial, i = sqrt(-1).
%H A275706 Robert Israel, <a href="/A275706/b275706.txt">Table of n, a(n) for n = 0..114</a>
%H A275706 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/q-Factorial.html">q-Factorial</a>.
%p A275706 a:= n-> Re(mul(((1+I)^j-1)/((1+I)-1), j=1..n)):
%p A275706 seq(a(n), n=0..20); # _Alois P. Heinz_, Sep 14 2016
%t A275706 Re@Table[QFactorial[n, 1 + I], {n, 0, 20}]
%Y A275706 Cf. A276688 (imaginary part), A005329.
%K A275706 sign
%O A275706 0,3
%A A275706 _Vladimir Reshetnikov_, Sep 13 2016