A090532 Let f(n) = n - pi(n). Then a(n) = least number of steps such that f(f(...(n)))=1.

1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 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, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9

Offset

2,3

Links

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

Example

a(10) = 3, 10 ->6 ->3 ->1.
a(100) = 9.
f(100) =100-25 = 75, f(75) = 75-21= 54, f(54) = 54-16 = 38, f(38) = 38-12= 26, f(26) = 26-9 = 17, f(17) = 17-7 = 10, f(10) = 10-4 =6, f(6) = 6-3=3, f(3) = 3-2 =1.

Crossrefs

Cf. A025003.

Sequence in context: A278163 A347635 A260999 * A003058 A000194 A168255

Adjacent sequences: A090529 A090530 A090531 * A090533 A090534 A090535

Keyword

nonn

Author

Amarnath Murthy, Dec 07 2003

Extensions

Corrected and extended by Sam Handler (sam_5_5_5_0(AT)yahoo.com), Dec 11 2004

Status

approved