a(n) = number of primes less than the square root of the (2^n)-th prime.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =5a(6) =7a(7) =9a(8) =12a(9) =17a(10) =24a(11) =32a(12) =45a(13) =61a(14) =82a(15) =114a(16) =154a(17) =215a(18) =293a(19) =404a(20) =557a(21) =766a(22) =1057a(23) =1459a(24) =2025a(25) =2800a(26) =3880a(27) =5379a(28) =7470a(29) =10368