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A128530
Nontrivial products of three lucky numbers.
0
27, 63, 81, 117, 135, 147, 189, 225, 243, 273, 279, 297, 315, 333, 343, 351, 387, 405, 441, 459, 507, 525, 567, 585, 603, 621, 637, 651, 657, 675, 693, 711, 729, 735, 777, 783, 819, 837, 891, 903, 945, 975, 999, 1029, 1035, 1053, 1071, 1125, 1143, 1161, 1183
OFFSET
1,1
COMMENTS
This is to lucky numbers (A000959) greater than 1 as A014612 (numbers that are divisible by exactly 3 primes, counted with multiplicity) are to primes. This is to 3 as A128462 (Nontrivial products of two lucky numbers) is to 2.
FORMULA
{A000959(i)*A000959(j)*A000959(k) for i, j, k > 1}.
MATHEMATICA
Lc = {3, 7, 9, 13, 15, 21, 25, 31, 33, 37, 43, 49, 51, 63, 67, 69, 73, 75, 79, 87, 93, 99, 105, 111, 115, 127, 129}; Select[Union[Times @@@ Tuples[{Lc, Lc, Lc}]], # <= 9 Max[Lc] &] (* Giovanni Resta, Jun 19 2016 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, May 07 2007
EXTENSIONS
Data corrected by Giovanni Resta, Jun 19 2016
STATUS
approved