A123906 a(n) = n-th integer from among those positive integers with at least n positive divisors.

1, 3, 8, 12, 24, 30, 54, 56, 100, 120, 144, 150, 288, 300, 324, 360, 560, 576, 756, 780, 990, 1020, 1050, 1056, 1980, 2040, 2100, 2184, 2352, 2376, 2808, 2856, 3900, 3960, 4032, 4080, 6000, 6048, 6120, 6160, 7980, 8064, 8400, 8568, 8580, 9000, 9072, 9120

Offset

1,2

Links

Table of n, a(n) for n=1..48.

Example

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.

Mathematica

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 *)

Crossrefs

Sequence in context: A209934 A007434 A128303 * A065970 A326890 A024463

Adjacent sequences: A123903 A123904 A123905 * A123907 A123908 A123909

Keyword

nonn

Author

Leroy Quet, Oct 28 2006

Extensions

Extended by Ray Chandler, Nov 13 2006

Status

approved