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

Author

Labos Elemer, Apr 13 2001

Keywords

• nonn

Comments

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

Examples

			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.
		

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

Crossrefs

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

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

Extensions

More terms from Jud McCranie, Apr 22 2001

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