A120633 Number of composite numbers bounded inclusively between p(n+1) and 2*p(n) where p(x) is prime(x).

1, 1, 3, 2, 7, 7, 12, 12, 13, 22, 19, 25, 31, 31, 33, 37, 45, 44, 51, 56, 55, 61, 63, 66, 75, 80, 81, 87, 88, 82, 101, 103, 111, 105, 121, 120, 124, 132, 134, 140, 148, 142, 158, 158, 164, 156, 165, 182, 188, 188, 189, 199, 193, 205, 210

Offset: 1

Author

Lekraj Beedassy, Jun 21 2006

Keywords

• nonn

Programs

Mathematica

Table[Count[Range[Prime[n+1],2Prime[n]],?CompositeQ],{n,60}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale, Oct 01 2019 *)

Formula

a(n) = A062234(n) - A070046(n) + 1 = A120632(n) - A040976(n+1).

Extensions

Definition clarified by Harvey P. Dale, Oct 01 2019