A064922 Number of iterations in A064920 to reach a prime.

0, 0, 1, 0, 2, 0, 1, 1, 3, 0, 3, 0, 2, 1, 2, 0, 2, 0, 2, 2, 4, 0, 4, 2, 3, 1, 4, 0, 4, 0, 1, 1, 3, 1, 3, 0, 3, 2, 4, 0, 4, 0, 3, 1, 5, 0, 3, 1, 3, 1, 3, 0, 3, 2, 3, 3, 5, 0, 3, 0, 2, 2, 2, 1, 3, 0, 3, 3, 3, 0, 4, 0, 4, 1, 5, 1, 3, 0, 3, 1, 5, 0, 3, 3, 4, 1, 3, 0, 5, 1, 4, 2, 4, 1, 4, 0, 3, 1, 5, 0, 5, 0, 3, 3, 4

Offset

2,5

Comments

a(p) = 0 for all primes p.

Links

Harry J. Smith, Table of n, a(n) for n = 2..1000

Example

a(18) = 2 as A064920(A064920(18)) = A064920(8) = 5 = A064921(18).

Prog

(PARI) gpf(n)= { local(f); f=factor(n)~; return(f[1, length(f)]) } { for (n=2, 1000, m=n; a=0; while (!isprime(m), g=gpf(m); m=m / g + g - 1; a++); write("b064922.txt", n, " ", a) ) } \\ Harry J. Smith, Sep 29 2009

Crossrefs

Cf. A064920, A064921, A064918.

Sequence in context: A135830 A339846 A029353 * A303337 A340502 A055186

Adjacent sequences: A064919 A064920 A064921 * A064923 A064924 A064925

Keyword

nonn

Author

Reinhard Zumkeller, Oct 14 2001

Status

approved