A060611 Smallest prime p such that n = A049108(p) = length of chain of iterates of Euler Phi starting with p.

2, 3, 5, 11, 17, 41, 83, 137, 257, 641, 1097, 2657, 5441, 10883, 17477, 40961, 65537, 140417, 295937, 557057, 1193537, 2384897, 4227137, 9548417, 17966357, 35946497, 71304257, 162174977, 305268737, 541073537, 1212153857, 2281701377

Offset

2,1

Comments

From 2nd to 12th term A007755 is the same as this sequence

Links

T. D. Noe, Table of n, a(n) for n=2..1002

Project Euler, Problem 214: Totient chains.

T. D. Noe, Computing Numbers in Section I of the Totient Iteration

Example

n=13: a(13)=2657 is the smallest prime which gives a chain of length 13, 2657 -> 2656 -> 1312 -> 640 -> 256 -> 128 -> 64 -> 32 -> 16 -> 8 -> 4 -> 2 -> 1, while the smallest number having this property is A007755(13) = 2329 -> 2176 -> 1024 -> 512 -> 256 -> 128 -> 64 -> 32 -> 16 -> 8 -> 4 -> 2 -> 1.

Crossrefs

Cf. A000010, A049108 = A003434 + 1, A007755, A049117.

A007755 has the same initial terms but is a different sequence.

Sequence in context: A085613 A082605 A007755 * A077497 A237995 A333081

Adjacent sequences: A060608 A060609 A060610 * A060612 A060613 A060614

Keyword

nonn

Author

Labos Elemer, Apr 13 2001

Extensions

More terms from Jud McCranie, Apr 22 2001

Removed duplicate cross references, added link, reformulated example. - M. F. Hasler, Oct 25 2008

Status

approved