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 A381268 #8 Feb 19 2025 13:37:32
%S A381268 1,4,256,1024,1048576,4194304,268435456,1073741824,17592186044416,
%T A381268 70368744177664,4503599627370496,18014398509481984,
%U A381268 18446744073709551616,73786976294838206464,4722366482869645213696,18889465931478580854784,4951760157141521099596496896,19807040628566084398385987584
%N A381268 a(n) = denominator( [(x*y*z*u)^n] 1/sqrt(1 - (x + y + z + u*(y + z))) ).
%H A381268 S. Hassani, J.-M. Maillard, and N. Zenine, <a href="https://arxiv.org/abs/2502.05543">On the diagonals of rational functions: the minimal number of variables (unabridged version)</a>, arXiv:2502.05543 [math-ph], 2025. See p. 24.
%F A381268 a(n) = denominator( [x^n] hypergeom( [1/2, 1/6, 1/2, 5/6], [1, 1, 1], 108*x) ).
%F A381268 a(n) = denominator( 2^(2*n-1) * 27^n * Gamma(n+1/6) * Gamma(n+1/2)^2 * Gamma(n+5/6)/(Pi^2 * (n!)^4) ).
%F A381268 a(2*n) = A278142(n).
%t A381268 a[n_]:=Denominator[SeriesCoefficient[1/Sqrt[1-(x+y+z+u(y+z))],{x,0,n},{y,0,n},{z,0,n},{u,0,n}]]; Array[a,13,0]
%Y A381268 Cf. A381267 (numerator).
%Y A381268 Cf. A009971, A134375, A278142.
%K A381268 nonn,frac
%O A381268 0,2
%A A381268 _Stefano Spezia_, Feb 18 2025