Number of primes < e^n.

Terms

a(0) =0a(1) =1a(2) =4a(3) =8a(4) =16a(5) =34a(6) =79a(7) =183a(8) =429a(9) =1019a(10) =2466a(11) =6048a(12) =14912a(13) =37128a(14) =93117a(15) =234855a(16) =595341a(17) =1516233a(18) =3877186a(19) =9950346a(20) =25614562a(21) =66124777a(22) =171141897a(23) =443963543a(24) =1154106844a(25) =3005936865a(26) =7842921261a(27) =20496470801a(28) =53645077679a(29) =140599114669