A137588 - OEIS

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A137588

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

4

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

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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