-1 + Product_{n>=1} 1/(1 + a(n)*x^n) = g.f. of A000040 (prime numbers).

Terms

a(0) =-2a(1) =1a(2) =1a(3) =4a(4) =4a(5) =13a(6) =16a(7) =44a(8) =52a(9) =112a(10) =182a(11) =411a(12) =620a(13) =1318a(14) =2142a(15) =5148a(16) =7676a(17) =15228a(18) =27530a(19) =58660a(20) =98372a(21) =207392a(22) =364464a(23) =763263a(24) =1341508a(25) =2773990a(26) =4923220a(27) =10470948a(28) =18510902a(29) =37546152