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a(n) = ((n mod d(n)) +1)th divisor of n, where d(n) is number of positive divisors of n.
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%I #11 Oct 11 2019 11:14:03

%S 1,1,3,2,5,3,7,1,1,5,11,1,13,7,15,2,17,1,19,4,3,11,23,1,5,13,27,14,29,

%T 15,31,4,3,17,35,1,37,19,39,1,41,3,43,4,9,23,47,24,7,5,51,26,53,27,55,

%U 1,3,29,59,1,61,31,9,2,5,3,67,4,3,35,71,1,73,37,15,38,7,39,79,1,3,41,83,1

%N a(n) = ((n mod d(n)) +1)th divisor of n, where d(n) is number of positive divisors of n.

%H Vincenzo Librandi, <a href="/A124332/b124332.txt">Table of n, a(n) for n = 1..10000</a>

%t f[n_] := Block[{d = Divisors[n]}, d[[Mod[n, Length[d]] + 1]]];Table[f[n], {n, 90}] (* _Ray Chandler_, Oct 26 2006 *)

%Y Cf. A000005, A122377, A124333.

%K nonn

%O 1,3

%A _Leroy Quet_ and _Ray Chandler_, Oct 26 2006