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A262599 Lexicographically earliest sequence of distinct terms such that, for any n > 0, phi(a(n)) = phi(n) (where phi denotes the Euler totient function), and a(n) > n if possible. 2

%I #13 Sep 25 2015 14:53:20

%S 2,1,4,6,8,3,9,10,14,12,22,5,21,18,16,20,32,7,27,24,26,11,46,30,33,28,

%T 38,36,58,15,62,34,44,40,39,42,57,54,45,48,55,13,49,50,52,23,94,60,86,

%U 66,64,56,106,19,75,70,63,29,118,17,77,31,74,68,104,25

%N Lexicographically earliest sequence of distinct terms such that, for any n > 0, phi(a(n)) = phi(n) (where phi denotes the Euler totient function), and a(n) > n if possible.

%C This is a permutation of the positive integers, with inverse A262603.

%C If the Carmichael's totient function conjecture is true, then this sequence has no fixed point.

%C For any n > 0, the orbit of n is finite, with length A066412(n).

%H Paul Tek, <a href="/A262599/b262599.txt">Table of n, a(n) for n = 1..10000</a>

%H Paul Tek, <a href="/A262599/a262599.cpp.txt">C99 program for this sequence</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%F a(n) = max(A066659(n), A049283(A000010(n))), for any n > 0.

%e phi(n) = 6 iff n is in { 7, 9, 14, 18 }.

%e Hence: a(7) = 9, a(9) = 14, a(14) = 18, a(18) = 7.

%o (C99) See Links section.

%Y Cf. A049283, A066412, A066659, A262603 (inverse).

%K nonn

%O 1,1

%A _Paul Tek_, Sep 25 2015

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Last modified June 8 08:55 EDT 2024. Contains 373207 sequences. (Running on oeis4.)