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Divisors of nonprimes not occurring earlier.
6

%I #5 Mar 30 2012 18:50:59

%S 1,2,4,3,6,8,9,5,10,12,7,14,15,16,18,20,21,11,22,24,25,13,26,27,28,30,

%T 32,33,17,34,35,36,19,38,39,40,42,44,45,23,46,48,49,50,51,52,54,55,56,

%U 57,29,58,60,31,62,63,64,65,66,68,69,70,72,37,74,75,76,77,78,80,81,41

%N Divisors of nonprimes not occurring earlier.

%C Permutation with inverse A137622; A137623(n) = a(a(n)).

%C a(A120632(n))=A000040(n); a(A120632(n)+1)=A100484(n); a(A137624(n))=A018252(n).

%H R. Zumkeller, <a href="/A137621/b137621.txt">Table of n, a(n) for n = 1..10001</a>

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

%e 1;2,4;3,6;8;9;5,10;12;7,14;15;16;18;20;21;11,22;24; .. .

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Jan 30 2008