Coefficient of x^n in Product_{k>=1} ((1+x^k)/(1-x^k))^(2*n).

A304447

Coefficient of x^n in Product_{k>=1} ((1+x^k)/(1-x^k))^(2*n).

Terms

    a(0) =1a(1) =4a(2) =40a(3) =448a(4) =5264a(5) =63624a(6) =783328a(7) =9770240a(8) =123040288a(9) =1561033348a(10) =19922193200a(11) =255472920256

External references