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A156238
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Smallest heptagonal number with n distinct prime factors.
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4
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7, 18, 286, 3010, 32890, 769230, 3333330, 159189030, 16015883940, 477463360374, 21643407275490, 1148540321999070, 18489352726664820, 4561561662153109614, 71000485538666794110, 14440652550858108745170, 927869754030522488795610
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(18) <= 150849873309136386205130310. - Donovan Johnson, Feb 15 2012
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LINKS
| Eric Weisstein's World of Mathematics, Heptagonal Numbers.
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EXAMPLE
| a(9) = 16015883940 = 2^2*3^2*5*7*17*19*23*29*59. 16015883940 is the smallest heptagonal number with 9 distinct prime factors.
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CROSSREFS
| Cf. A000566, A076551, A156236, A156237, A156239.
Sequence in context: A198023 A202761 A196219 * A156295 A070414 A195870
Adjacent sequences: A156235 A156236 A156237 * A156239 A156240 A156241
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KEYWORD
| nonn,changed
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AUTHOR
| Donovan Johnson (donovan.johnson(AT)yahoo.com), Feb 07 2009
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EXTENSIONS
| a(17) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jul 02 2011
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