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

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =17a(5) =38a(6) =112a(7) =280a(8) =882a(9) =2416a(10) =8253a(11) =24458a(12) =91051a(13) =289704a(14) =1172288a(15) =3980034a(16) =17413820a(17) =62706119a(18) =294608079a(19) =1118820630a(20) =5603910081a(21) =22328924231a(22) =118432939871a(23) =492897768426