A137588 Number of primes not greater than n that are greater than the number of primes not greater than n.

0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14

Offset

1,7

Comments

a(n) = #{p prime: A000720(n)<p<=n} = A000720(n)-A132090(n);

a(A007821(n)) = n.

Links

R. Zumkeller, Table of n, a(n) for n = 1..10000

Example

n=100: A000720(100)=25,
a(100)=#{29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97}=16.

Mathematica

Table[PrimePi[n]-PrimePi[PrimePi[n]], {n, 90}]  (* Harvey P. Dale, Mar 20 2011 *)

Crossrefs

Sequence in context: A054895 A194699 A262694 * A033271 A290792 A279757

Adjacent sequences: A137585 A137586 A137587 * A137589 A137590 A137591

Keyword

nonn

Author

Reinhard Zumkeller, Jan 28 2008

Status

approved