Number of primes between n and 3n.

Terms

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