a(n) = n^2 - previousprime(n)*nextprime(n), for n>2.

Terms

a(0) =-1a(1) =1a(2) =4a(3) =1a(4) =-6a(5) =-13a(6) =4a(7) =23a(8) =30a(9) =1a(10) =-18a(11) =-25a(12) =4a(13) =35a(14) =42a(15) =1a(16) =-30a(17) =-37a(18) =4a(19) =47a(20) =-22a(21) =-91a(22) =-42a(23) =9a(24) =62a(25) =117a(26) =128a(27) =1a(28) =-112a(29) =-123