Number of times that i and 2n-i are both prime, for i = 1, ..., 2n-1.

Terms

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