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A048692
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Triangle read by rows in which row n contains first n numbers with exactly n distinct prime factors.
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7
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2, 6, 10, 30, 42, 60, 210, 330, 390, 420, 2310, 2730, 3570, 3990, 4290, 30030, 39270, 43890, 46410, 51870, 53130, 510510, 570570, 690690, 746130, 870870, 881790, 903210, 9699690, 11741730, 13123110, 14804790, 15825810, 16546530, 17160990
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 2; 6 10; 30 42 60; 210 330 390 420; ...
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MATHEMATICA
| f[n_] := Flatten[Table[ # [[1]]] & /@ FactorInteger[n]]; (* for n=7 *) Take[ Select[ Range[10^7], Length[f[ # ]] == 7 & ], 7]
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CROSSREFS
| Cf. primorial numbers A002110.
Sequence in context: A032374 A074095 A079855 * A019095 A026117 A107385
Adjacent sequences: A048689 A048690 A048691 * A048693 A048694 A048695
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KEYWORD
| nonn,tabl
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 20 2002
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EXTENSIONS
| Edited, corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 22 2002
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