

A079852


a(1) = 1, a(2) = 2, a(3) = 3 and a(n) is the smallest number such that all a(i)*a(j)*a(k) are different.


4



1, 2, 3, 4, 5, 7, 9, 11, 13, 16, 17, 19, 23, 25, 29, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 210, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 289, 293, 307, 311, 313, 317, 331
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OFFSET

1,2


COMMENTS

Note that a(57) = 210 = 2*3*5*7, while 330 = 2*3*5*11 is not in the sequence. This demonstrates that this sequence is not determined by prime signature alone.  Charles R Greathouse IV, Oct 17 2015


LINKS

Zak Seidov, Table of n, a(n) for n = 1..200


MATHEMATICA

f[l_List] := Block[{k = 1, p2 = Times @@@ Subsets[l, {2}], p3 = Times @@@ Subsets[l, {3}]}, While[Intersection[p3, p2*k] != {}, k++ ]; Append[l, k]]; Nest[f, {1, 2, 3}, 62] (* Ray Chandler, Feb 12 2007 *)


CROSSREFS

Cf. A000045, A079850, A066720, A026477.
Sequence in context: A089237 A009087 A026477 * A084400 A050376 A280257
Adjacent sequences: A079849 A079850 A079851 * A079853 A079854 A079855


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Feb 19 2003


EXTENSIONS

Extended by Ray Chandler, Feb 12 2007
Typo in name fixed by Zak Seidov, Jul 06 2013


STATUS

approved



