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

Terms

a(0) =1a(1) =4a(2) =16a(3) =60a(4) =192a(5) =596a(6) =1744a(7) =4892a(8) =13248a(9) =34868a(10) =89296a(11) =223660a(12) =548928a(13) =1323060a(14) =3137520a(15) =7332332a(16) =16907584a(17) =38517444a(18) =86777328a(19) =193523404a(20) =427562816a(21) =936555044a(22) =2035286576a(23) =4390850268a(24) =9409096576a(25) =20037827876a(26) =42429318480a(27) =89369282460a(28) =187325508288