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 A381197 #10 Feb 19 2025 13:38:04
%S A381197 1,9,1575,107415,143918775,13539797271,5492167201521,586937023583625,
%T A381197 4173054453859037175,477630312182609961375,223908157536370130248425,
%U A381197 26751307348701533866638825,51959852697049291288154030625,6393039919009116988875533492625,3182668486503393355366954041669375
%N A381197 a(n) = numerator( [(x*y*z*u)^n] 1/sqrt(1 - (x + y + z + u*(x*y + x*z + y*z))) ).
%H A381197 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.
%t A381197 a[n_]:=Numerator[SeriesCoefficient[1/Sqrt[1-(x+y+z+u*(x*y+x*z+y*z))],{x,0,n},{y,0,n},{z,0,n},{u,0,n}]]; Array[a,15,0]
%Y A381197 Cf. A268554, A381198 (denominators).
%K A381197 nonn,frac
%O A381197 0,2
%A A381197 _Stefano Spezia_, Feb 16 2025