G.f. A(x) satisfies: x = Sum_{n>=1} x^n * (1+x)^(n^2/2) / A(x)^(n/2).

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =11a(5) =21a(6) =49a(7) =133a(8) =408a(9) =1376a(10) =5020a(11) =19564a(12) =80741a(13) =350551a(14) =1593066a(15) =7547792a(16) =37163568a(17) =189662934a(18) =1001046684a(19) =5453972462a(20) =30622950955a(21) =176942133603