Number of irregular primes less than 2^n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =2a(6) =5a(7) =9a(8) =28a(9) =64a(10) =124a(11) =225a(12) =408a(13) =763a(14) =1378a(15) =2566a(16) =4803a(17) =9005a(18) =16948a(19) =32300a(20) =61408a(21) =116688a(22) =222093a(23) =424411a(24) =812236a(25) =1556827a(26) =2991345a(27) =5756015a(28) =11089585a(29) =21403049