a(n) = -prime(n) if prime(n) is an irregular prime else prime(n).

Terms

a(0) =2a(1) =3a(2) =5a(3) =7a(4) =11a(5) =13a(6) =17a(7) =19a(8) =23a(9) =29a(10) =31a(11) =-37a(12) =41a(13) =43a(14) =47a(15) =53a(16) =-59a(17) =61a(18) =-67a(19) =71a(20) =73a(21) =79a(22) =83a(23) =89a(24) =97a(25) =-101a(26) =-103a(27) =107a(28) =109a(29) =113