Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(3^k).

Terms

a(0) =1a(1) =6a(2) =36a(3) =200a(4) =1038a(5) =5160a(6) =24776a(7) =115632a(8) =527172a(9) =2355998a(10) =10349448a(11) =44783064a(12) =191211512a(13) =806737800a(14) =3367294320a(15) =13918479872a(16) =57020736942a(17) =231697484304a(18) =934399998412