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

Terms

a(0) =1a(1) =2a(2) =2a(3) =6a(4) =10a(5) =18a(6) =42a(7) =78a(8) =154a(9) =314a(10) =626a(11) =1246a(12) =2498a(13) =4994a(14) =9970a(15) =19974a(16) =39930a(17) =79826a(18) =159706a(19) =319374a(20) =638714a(21) =1277530a(22) =2554978a(23) =5109854a(24) =10219922a(25) =20439714a(26) =40879234a(27) =81758854a(28) =163517466a(29) =327034514