Expansion of Product_{k>=1} 1 / (1 - x^k)^(4^(k-1)).

Terms

a(0) =1a(1) =1a(2) =5a(3) =21a(4) =95a(5) =415a(6) =1851a(7) =8155a(8) =36030a(9) =158510a(10) =696502a(11) =3052966a(12) =13359230a(13) =58346206a(14) =254405630a(15) =1107479694a(16) =4813850699a(17) =20894227355a(18) =90567536543a(19) =392066476815