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%I #9 Aug 01 2015 21:30:53
%S 4,6,8,10,9,14,12,15,16,22,18,26,20,21,24,34,27,38,25,28,30,46,32,35,
%T 36,33,40,58,39,62,42,44,48,45,50,74,52,51,54,82,49,86,55,57,56,94,60,
%U 63,64,66,65,106,68,70,72,69,76,118,75,122,78,77,80,85,81,134,84,87,88,142
%N a(n) = the smallest integer > n that has yet to occur in the sequence, and that is not coprime to n.
%C Is this a permutation of the composite integers?
%t g[n_] := g[n] = Block[{k = n + 1, t = Table[ g@i, {i, 2, n - 1}]}, While[ MemberQ[t, k] || GCD[n, k] == 1, k++ ]; k]; Table[ g@n, {n, 2, 71}] (* or *) f[lst_] := Block[{len = 2 + Length@lst}, k = 1 + len; While[ MemberQ[lst, k] || GCD[len, k] == 1, k++ ]; Append[lst, k]]; Nest[f, {}, 70] (* _Robert G. Wilson v_, Aug 17 2009 *)
%K nonn
%O 2,1
%A _Leroy Quet_, Jul 07 2009
%E a(17) and further terms from _Robert G. Wilson v_, Aug 17 2009
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