Number of primes between n and 4n+1.

Terms

a(0) =3a(1) =4a(2) =5a(3) =5a(4) =6a(5) =6a(6) =7a(7) =7a(8) =8a(9) =9a(10) =10a(11) =10a(12) =11a(13) =10a(14) =12a(15) =12a(16) =13a(17) =14a(18) =14a(19) =14a(20) =15a(21) =16a(22) =16a(23) =16a(24) =17a(25) =18a(26) =20a(27) =21a(28) =21a(29) =20