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

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =28a(5) =85a(6) =252a(7) =745a(8) =2202a(9) =6530a(10) =19326a(11) =57194a(12) =169341a(13) =501242a(14) =1483816a(15) =4392531a(16) =13002772a(17) =38491212a(18) =113943278a(19) =337298400a(20) =998482338a(21) =2955742400a(22) =8749688247a(23) =25901125616a(24) =76673399424a(25) =226971213462a(26) =671887935923