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Search: id:A117879
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| A117879 |
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First semiprime after e^n. |
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+0
1
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| 4, 4, 9, 21, 55, 155, 407, 1099, 2981, 8105, 22033, 59881, 162757, 442417, 1202611, 3269021, 8886117, 24154953, 65659981, 178482301, 485165203, 1318815739, 3584912849, 9744803447, 26489122131, 72004899341, 195729609431
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Semiprime analogue of A074496 = first prime after e^n. Lim_[n approaches infinity] a(n+1)/a(n) = e. There are numbers where floor(e^n) is itself a semiprime, as with floor(e^6) = 403 = 13 * 31, floor(e^15) = 3269017 = 773 * 4229, floor(e^20) = 485165195 = 5 * 97033039, floor(e^22) = 3584912846 = 2 * 1792456423, floor(e^24) = 26489122129 = 103 * 257175943.
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LINKS
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Eric Weisstein's World of Mathematics, e-Prime.
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FORMULA
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a(n) = Smallest semiprime > e^n. Smallest semiprime > floor(e^n). a(n) = min{s > A000149(n) and s in A001358}.
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CROSSREFS
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Cf. A000040, A000149, A001358, A007512, A014210, A050808, A050809, A059303, A064118, A095935, A115019, A074496, A118840.
Sequence in context: A135065 A067553 A112683 this_sequence A069549 A118069 A089539
Adjacent sequences: A117876 A117877 A117878 this_sequence A117880 A117881 A117882
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KEYWORD
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easy,nonn,less
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), May 02 2006
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