A107609 a(n) = round(n / pi(n)) = round(A000027(n) / A000720(n)).

2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 3, 4, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

Offset

2,1

Comments

This sequence grows very slowly. The first n for which a(n) = 5 is 190, then 556 for 6, 1821 for 7, etc. - Alonso del Arte, Feb 27 2012

Links

Table of n, a(n) for n=2..106.

Example

a(6) = 2 because pi(6) = 3 and 6/3 = 2.
a(7) = 2 because pi(7) = 4 and 7/4 = 1.75, which rounds up to 2.

Mathematica

Table[ Round[ n / PrimePi[ n]], {n, 2, 106}]

Crossrefs

Cf. A000720, A107610, A107614, A272231.

Sequence in context: A111859 A156822 A130635 * A243113 A258198 A204562

Adjacent sequences: A107606 A107607 A107608 * A107610 A107611 A107612

Keyword

nonn

Author

Jonathan Vos Post and Robert G. Wilson v, May 17 2005

Status

approved