Irregular primes with irregularity index three.

Terms

a(0) =491a(1) =617a(2) =647a(3) =1151a(4) =1217a(5) =1811a(6) =1847a(7) =2939a(8) =3833a(9) =4003a(10) =4657a(11) =4951a(12) =6763a(13) =7687a(14) =8831a(15) =9011a(16) =10463a(17) =10589a(18) =12073a(19) =13217a(20) =14533a(21) =14737a(22) =14957a(23) =15287a(24) =15787a(25) =15823a(26) =16007a(27) =17681a(28) =17863a(29) =18713