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 A015034 #10 Sep 08 2022 08:44:39
%S A015034 1,1,17,4433,18245201,1197172898385,1255709588423576145,
%T A015034 21068918017101222558779985,5655752483351603939678821837720145,
%U A015034 24291387778773301588924456932322615789898321
%N A015034 q-Catalan numbers (binomial version) for q=4.
%H A015034 G. C. Greubel, <a href="/A015034/b015034.txt">Table of n, a(n) for n = 0..41</a>
%F A015034 a(n) = binomial(2*n, n, q)/(n+1)_q, where binomial(n,m,q) is the q-binomial coefficient, with q=4.
%F A015034 a(n) = ((1-q)/(1-q^(n+1)))*Product_{k=0..(n-1)} (1-q^(2*n-k))/(1-q^(k+1)), with q=4. - _G. C. Greubel_, Nov 11 2018
%t A015034 Table[3*QBinomial[2 n, n, 4]/(4^(n + 1) - 1), {n, 0, 20}] (* _G. C. Greubel_, Nov 11 2018 *)
%o A015034 (PARI) q=4; for(n=0, 20, print1(((1-q)/(1-q^(n+1)))*prod(k=0,n-1, (1-q^(2*n-k))/(1-q^(k+1))), ", ")) \\ _G. C. Greubel_, Nov 11 2018
%o A015034 (Magma) q:=4; [1] cat [((1-q)/(1-q^(n+1)))*(&*[(1-q^(2*n-k))/(1-q^(k+1)): k in [0..n-1]]): n in [1..20]]; // _G. C. Greubel_, Nov 11 2018
%Y A015034 Cf. A015030 (q=2).
%K A015034 nonn,easy
%O A015034 0,3
%A A015034 _Olivier Gérard_