A087724 a(n) = -PrimePi(n) +floor( prime(n)/log(n))-2.

1, 0, 1, 1, 2, 2, 3, 4, 6, 5, 7, 7, 8, 9, 11, 11, 12, 12, 13, 13, 15, 15, 17, 19, 19, 20, 21, 20, 21, 23, 24, 26, 26, 28, 29, 29, 30, 31, 32, 33, 33, 34, 35, 35, 35, 37, 40, 41, 41, 42, 43, 42, 44, 46, 47, 48, 48, 48, 49, 48, 50, 54, 54, 54, 55, 57, 58, 60, 61, 60, 61, 62, 63, 64

Offset: 2

Author

Roger L. Bagula, Sep 29 2003

Keywords

• nonn

Programs

Maple

A087724 := proc(n)
    floor( ithprime(n)/log(n))-numtheory[pi](n) -2 ;
end proc: # R. J. Mathar, May 15 2013

Mathematica

Digits=200 a[n_]=-PrimePi[n]+Floor[Prime[n]/Log[n]]-2 b=Table[a[n], {n, 2, Digits}]

Formula

a(n) = A085581(n)-A000720(n) -2. - R. J. Mathar, May 15 2013