A060197 Start at n, repeatedly apply pi(x) until reach 0; a(n) = number of steps to reach 0.

2, 3, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7

Offset

1,1

Comments

The numbers at which this sequence jumps from n to n+1 are A007097(n).

Links

Table of n, a(n) for n=1..105.

Formula

Table[Length[FixedPointList[PrimePi, w]]-1, {w, 1, 1000}]

Example

For n=1000, the corresponding sequence of PrimePi-iteration is {1000,168,39,12,5,3,2,1,0}, whose length is a(1000)=9.

Crossrefs

Cf. A007097, A000720.

Sequence in context: A030602 A133947 A082090 * A116487 A249041 A070546

Adjacent sequences: A060194 A060195 A060196 * A060198 A060199 A060200

Keyword

nonn

Author

Labos Elemer, Mar 19 2001

Extensions

Offset corrected by Sean A. Irvine, Oct 30 2022

Status

approved