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

1,3

Links

Table of n, a(n) for n=1..55.

Formula

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

Mathematica

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

Crossrefs

Sequence in context: A199183 A178908 A198552 * A095353 A324876 A226370

Adjacent sequences: A120630 A120631 A120632 * A120634 A120635 A120636

Keyword

nonn

Author

Lekraj Beedassy, Jun 21 2006

Extensions

Definition clarified by Harvey P. Dale, Oct 01 2019

Status

approved