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%I #22 Feb 14 2016 14:56:12
%S 1,2,3,6,4,9,5,12,20,29,7,16,8,19,33,48,10,24,11,27,46,67,13,32,55,80,
%T 106,133,14,36,15,39,68,99,132,167,17,43,75,111,18,47,21,53,91,135,22,
%U 57,98,146,196,247,23,60,105,157,212,269,25,64,26,69,121,180,242,307,28
%N a(1) = 1; a(n) = smallest positive integer not occurring earlier in sequence if n is a prime. a(n) = a(n-1)th smallest positive integer among those not occurring earlier in sequence if n is composite.
%C Sequence is a permutation of the positive integers.
%H Ivan Neretin, <a href="/A103864/b103864.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%e Since 6 is composite, a(6) = a(5)th (4th) smallest positive integer not occurring earlier in sequence. The terms not occurring earlier in sequence are 5,7,8,9,10... and the 4th of these is 9.
%t a = {1}; Do[AppendTo[a, Complement[Range[Max[a] + a[[-1]] + 1], a][[If[PrimeQ[n], 1, a[[-1]]]]]], {n, 2, 67}]; a (* _Ivan Neretin_, May 09 2015 *)
%Y Inverse: A103866.
%Y Cf. A103865, A103867 (variant and its inverse).
%K nonn,look
%O 1,2
%A _Leroy Quet_, Feb 18 2005
%E More terms from _John W. Layman_, May 27 2005
%E Corrected by _Franklin T. Adams-Watters_, Nov 22 2006