Number of solutions to n=p+q where p and q are primes or zero.

Terms

a(0) =1a(1) =0a(2) =2a(3) =2a(4) =1a(5) =4a(6) =1a(7) =4a(8) =2a(9) =2a(10) =3a(11) =2a(12) =2a(13) =4a(14) =3a(15) =2a(16) =4a(17) =2a(18) =4a(19) =4a(20) =4a(21) =2a(22) =5a(23) =2a(24) =6a(25) =2a(26) =5a(27) =0a(28) =4a(29) =2