a(n) is the n-th prime = -1 (mod n).

Terms

a(0) =2a(1) =5a(2) =11a(3) =19a(4) =89a(5) =41a(6) =181a(7) =127a(8) =251a(9) =199a(10) =571a(11) =227a(12) =1013a(13) =433a(14) =599a(15) =751a(16) =2039a(17) =593a(18) =2089a(19) =859a(20) =1637a(21) =1429a(22) =4001a(23) =1103a(24) =4049a(25) =2053a(26) =3779a(27) =2267a(28) =6263a(29) =1499