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

Terms

a(0) =1a(1) =4a(2) =16a(3) =56a(4) =176a(5) =520a(6) =1456a(7) =3896a(8) =10048a(9) =25100a(10) =60960a(11) =144440a(12) =334752a(13) =760456a(14) =1696464a(15) =3722224a(16) =8043040a(17) =17135624a(18) =36031104a(19) =74840568a(20) =153680928a(21) =312198160a(22) =627828272a(23) =1250540024a(24) =2468443296a(25) =4830809868a(26) =9377190336a(27) =18061370288a(28) =34531009760a(29) =65552873736