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

Author

Labos Elemer, Mar 19 2001

Keywords

• nonn

Comments

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

Examples

			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.

Formula

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

Extensions

Offset corrected by Sean A. Irvine, Oct 30 2022