a(n) = number of primes of the form k*(n-k) + 1.

Terms

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