Expansion of g.f.: 1/(Sum_{p prime} x^p)^2.

Terms

a(0) =1a(1) =-2a(2) =3a(3) =-6a(4) =11a(5) =-20a(6) =36a(7) =-62a(8) =107a(9) =-186a(10) =319a(11) =-544a(12) =924a(13) =-1560a(14) =2628a(15) =-4416a(16) =7393a(17) =-12346a(18) =20571a(19) =-34198a(20) =56749a(21) =-94004a(22) =155448a(23) =-256668a(24) =423206a(25) =-696884a(26) =1146158a(27) =-1882928a(28) =3089996a(29) =-5065826