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A114057
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Start of record gap in odd semiprimes A046315.
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0
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9, 25, 39, 95, 267, 2369, 6559, 8817, 13705, 15261, 21583, 35981, 66921, 113009, 340891, 783757, 872219, 3058853, 3586843, 5835191, 12345473, 108994623, 248706917, 268749691, 679956119, 709239621, 3648864859, 3790337723
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 3 of the first 5 values of record gaps in odd semiprimes are also record merits = [A046315(k+1)-A046315(k)]/log(A046315(k)]/), namely: (15 - 9) / log(9) = 6.28770982; (111 - 95) / log(95) = 8.09010923; (287 - 267) / log(267) = 8.24228608. It is easy to prove that there are gaps of arbitrary length in even semiprimes (A100484); can we prove that there are gaps of arbitrary length in odd semiprimes (A046315) and in semiprimes (A001358)?
The record gaps have lengths 6, 8, 10, 16, 20, 22, 24, 26, 28, 32, 36, 38, 40, 44, 50, 52, 60, 64, 70, 74. - T. D. Noe (noe(AT)sspectra.com), Feb 03 2006
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FORMULA
| {a(n)} = {A046315(k) such that A046315(k+1)-A046315(k) is a record}.
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EXAMPLE
| a(1) = A046315(2)-A046315(1) = 15 - 9 = 6.
a(2) = A046315(5)-A046315(4) = 33 - 25 = 8.
a(3) = A046315(8)-A046315(7) = 49 - 39 = 10.
a(4) = A046315(20)-A046315(19) = 111 - 95 = 16.
a(5) = A046315(55)-A046315(54) = 287 - 267 = 20.
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MATHEMATICA
| f[n_] := Block[{k = n + 2}, While[ Plus @@ Last /@ FactorInteger@k != 2, k += 2]; k]; lst = {}; d = 0; a = b = 9; Do[{a, b} = {b, f[a]}; If[b - a > d, d = b - a; AppendTo[lst, a]], {n, 10^8}]; lst (* Robert G. Wilson v *)
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CROSSREFS
| Cf. A001358, A046315, A065516, A085809, A100484, A114412, A114021.
Sequence in context: A147199 A147403 A044451 * A031036 A051132 A075026
Adjacent sequences: A114054 A114055 A114056 * A114058 A114059 A114060
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 02 2006
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(at)rgwv.com) and T. D. Noe (noe(AT)sspectra.com), Feb 03 2006
a(23)-a(28) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Mar 14 2010
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