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a(n) is the smallest positive integer such that floor(a(n)/d(a(n))) = n, or -1 if no such number exists, where d(m) is the number of positive divisors of m.
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%I #15 Jul 01 2022 10:49:10

%S 1,5,7,28,11,13,44,17,19,63,23,51,55,29,31,49,69,37,77,41,43,91,47,

%T 147,153,53,111,115,59,61,125,129,67,207,71,73,296,155,79,121,83,680,

%U 261,89,183,185,284,97,399,101,103,209,107,109,221,113,459,235,237,363,247,249

%N a(n) is the smallest positive integer such that floor(a(n)/d(a(n))) = n, or -1 if no such number exists, where d(m) is the number of positive divisors of m.

%H Hugo van der Sanden and D. W. Wilson, <a href="/A126888/b126888.txt">Table of n, a(n) for n = 1..10000</a>

%t f[n_] := Block[{k = 1},While[Floor[k/Length[Divisors[k]]] != n, k++ ];k];Table[f[n], {n, 62}] (* _Ray Chandler_, Jan 04 2007 *)

%Y Cf. A000005, A126889, A078709, A125056, A125057.

%K nonn

%O 1,2

%A _Leroy Quet_, Dec 30 2006

%E Extended by _Ray Chandler_, Jan 04 2007.

%E Added escape clause to definition at the suggestion of _Hugo van der Sanden_. - _N. J. A. Sloane_, Jul 01 2022