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 A369386 #5 Jan 22 2024 10:39:03
%S A369386 1,2,4,8,18,48,138,428,1392,4652,15884,55124,193724,688008,2465134,
%T A369386 8899700,32342236,118215780,434314138,1602935104,5940303754,
%U A369386 22095769648,82464791420,308715131744,1158949678600,4362040367048,16456820491806,62223707844096
%N A369386 a(n) is the constant term in expansion of Product_{k=1..n} (x^(2*k-1) + 1/x^(2*k-1))^2.
%t A369386 Table[Coefficient[Product[(x^(2 k - 1) + 1/x^(2 k - 1))^2, {k, 1, n}], x, 0], {n, 0, 27}]
%Y A369386 Cf. A047653, A156181, A156700, A292476.
%K A369386 nonn
%O A369386 0,2
%A A369386 _Ilya Gutkovskiy_, Jan 22 2024