a(n) is the first prime value of the n-th cyclotomic polynomial.

Terms

a(0) =2a(1) =2a(2) =3a(3) =2a(4) =5a(5) =3a(6) =7a(7) =2a(8) =3a(9) =11a(10) =11a(11) =13a(12) =13a(13) =43a(14) =151a(15) =2a(16) =17a(17) =46441a(18) =19a(19) =61681a(20) =368089a(21) =683a(22) =23a(23) =241a(24) =5a(25) =2731a(26) =3a(27) =15790321a(28) =29a(29) =331