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a(n) = n-th integer from among those positive integers with at least n positive divisors.
0

%I #12 Nov 01 2019 10:27:41

%S 1,3,8,12,24,30,54,56,100,120,144,150,288,300,324,360,560,576,756,780,

%T 990,1020,1050,1056,1980,2040,2100,2184,2352,2376,2808,2856,3900,3960,

%U 4032,4080,6000,6048,6120,6160,7980,8064,8400,8568,8580,9000,9072,9120

%N a(n) = n-th integer from among those positive integers with at least n positive divisors.

%e The sequence of positive integers, each with 4 or more positive divisors, begins: 6,8,10,12,14,... The 4th of these is 12, so a(4) = 12.

%t f[n_] := Block[{k = 0, c = n},While[c > 0,k++;While[Length@Divisors[k] < n, k++ ];c--;];k];Table[f[n], {n, 50}] (* _Ray Chandler_, Nov 13 2006 *)

%K nonn

%O 1,2

%A _Leroy Quet_, Oct 28 2006

%E Extended by _Ray Chandler_, Nov 13 2006