a(n) is the constant term in expansion of Product_{k=1..n} (x^(2*k-1) + 1/x^(2*k-1))^2.
A369386
a(n) is the constant term in expansion of Product_{k=1..n} (x^(2*k-1) + 1/x^(2*k-1))^2.
Terms
- a(0) =1a(1) =2a(2) =4a(3) =8a(4) =18a(5) =48a(6) =138a(7) =428a(8) =1392a(9) =4652a(10) =15884a(11) =55124a(12) =193724a(13) =688008a(14) =2465134a(15) =8899700a(16) =32342236a(17) =118215780a(18) =434314138a(19) =1602935104a(20) =5940303754a(21) =22095769648a(22) =82464791420a(23) =308715131744
External references
- oeis: A369386