Sum of the first 2^n primes.

Terms

a(0) =2a(1) =5a(2) =17a(3) =77a(4) =381a(5) =1851a(6) =8893a(7) =41741a(8) =191755a(9) =868151a(10) =3875933a(11) =17120309a(12) =74950547a(13) =325590115a(14) =1405167561a(15) =6029676711a(16) =25750781177a(17) =109495928099a(18) =463852117169