a(n) = (prime(n+1) - 1)/4 if this is an integer or (prime(n+1) + 1)/4 otherwise.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =3a(5) =4a(6) =5a(7) =6a(8) =7a(9) =8a(10) =9a(11) =10a(12) =11a(13) =12a(14) =13a(15) =15a(16) =15a(17) =17a(18) =18a(19) =18a(20) =20a(21) =21a(22) =22a(23) =24a(24) =25a(25) =26a(26) =27a(27) =27a(28) =28a(29) =32