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%I #12 Oct 26 2019 18:03:21
%S 1,2,5,3,4,8,9,7,11,6,13,17,10,16,19,15,14,20,21,23,25,12,29,31,18,22,
%T 37,27,26,28,33,35,32,24,41,43,30,34,47,39,38,40,45,49,44,36,53,55,46,
%U 52,59,51,50,56,57,61,62,42,67,71,48,58,65,63,64,68,69,73,74,54,77,79
%N a(n) is the smallest positive integer which does not occur earlier in the sequence such that gcd(n(n+1)/2, a(n)) = 1.
%C Sequence is a permutation of the positive integers.
%H Diana Mecum, <a href="/A118460/b118460.txt">Table of n, a(n) for n = 1..500</a>
%e Of the positive integers (6,7,8,...) not occurring among the first 5 terms of the sequence, 8 is the lowest coprime to 6*7/2 = 21. So a(6) = 8. a(6) is not 6 or 7 because gcd(6,21) > 1 and gcd(7,21) > 1.
%Y Cf. A118461, A000217.
%K nonn
%O 1,2
%A _Leroy Quet_, Apr 28 2006
%E More terms from _Diana L. Mecum_, Jul 15 2007
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