A039651 Number of iterations of f(x) = phi(x)+1 on n required to reach a prime.

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

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A039649, A039650, A039651, A039652, A039653, A039654, A039655, A039656.

Programs

Mathematica

Table[Length[NestWhileList[EulerPhi[#] + 1 &, n, UnsameQ, All]] - 2, {n, 100}] (* T. D. Noe, Oct 17 2013 *)