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

%I A060611 #16 Oct 15 2013 22:30:59
%S A060611 2,3,5,11,17,41,83,137,257,641,1097,2657,5441,10883,17477,40961,65537,
%T A060611 140417,295937,557057,1193537,2384897,4227137,9548417,17966357,
%U A060611 35946497,71304257,162174977,305268737,541073537,1212153857,2281701377
%N A060611 Smallest prime p such that n = A049108(p) = length of chain of iterates of Euler Phi starting with p.
%C A060611 From 2nd to 12th term A007755 is the same as this sequence
%H A060611 T. D. Noe, <a href="/A060611/b060611.txt">Table of n, a(n) for n=2..1002</a>
%H A060611 Project Euler, <a href="http://projecteuler.net/index.php?section=problems&amp;id=214">Problem 214: Totient chains</a>.
%H A060611 T. D. Noe, <a href="http://www.sspectra.com/math/IteratedPhi2.pdf">Computing Numbers in Section I of the Totient Iteration</a>
%e A060611 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.
%Y A060611 Cf. A000010, A049108 = A003434 + 1, A007755, A049117.
%Y A060611 A007755 has the same initial terms but is a different sequence.
%K A060611 nonn
%O A060611 2,1
%A A060611 _Labos Elemer_, Apr 13 2001
%E A060611 More terms from _Jud McCranie_, Apr 22 2001
%E A060611 Removed duplicate cross references, added link, reformulated example. - _M. F. Hasler_, Oct 25 2008