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A115186
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Smallest number m such that m and m+1 have exactly n prime factors (counted with multiplicity).
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4
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2, 9, 27, 135, 944, 5264, 29888, 50624, 203391, 3290624, 6082047, 32535999, 326481920, 3274208000, 6929459199, 72523096064, 37694578688, 471672487935, 11557226700800, 54386217385983, 50624737509375, 275892612890624
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A001222(a(n)) = A001222(a(n)+1) = n: subsequence of A045920;
a(16) > 4*10^10 - Martin Fuller (martin_n_fuller(AT)btinternet.com), Jan 17 2006
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REFERENCES
| J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 135, p. 46, Ellipses, Paris 2008.
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EXAMPLE
| a(10) = 3290624 = 6427 * 2^9, 3290624+1 = 13 * 5^5 * 3^4:
A001222(13290624) = A001222(13290625) = 10.
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CROSSREFS
| Cf. A001222, A045920, A052215, A093548.
Sequence in context: A123904 A128239 A019065 * A090900 A155472 A100293
Adjacent sequences: A115183 A115184 A115185 * A115187 A115188 A115189
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 16 2006
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EXTENSIONS
| a(13)-a(15) from Martin Fuller (martin_n_fuller(AT)btinternet.com), Jan 17 2006
a(16), a(17) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 08 2008
a(18)-a(22) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jan 21 2009
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