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Search: id:A136152
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| A136152 |
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Composites one larger than a prime and with exactly three distinct prime factors. |
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+0
5
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| 30, 42, 60, 84, 90, 102, 110, 114, 132, 138, 140, 150, 168, 174, 180, 182, 198, 228, 230, 234, 240, 252, 258, 264, 270, 282, 294, 308, 312, 318, 348, 350, 354, 360, 374, 380, 402, 410, 434, 440, 444, 450, 468, 480, 492, 504, 522, 558, 564, 572, 588, 594, 600
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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Find primes followed by N with exactly three prime factors, without repetition.
Equals A008864 INTERSECT A033992. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 20 2008
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EXAMPLE
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a(0)=30 because 30 follows the prime 29, and has three factors 2, 3, and 5.
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MAPLE
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isA008864 := proc(n) if n -prevprime(n) = 1 then true ; else false ; fi ; end: isA033992 := proc(n) if nops(numtheory[factorset](n)) = 3 then true ; else false ; fi ; end: isA136152 := proc(n) isA008864(n) and isA033992(n) ; end: for n from 1 do p := ithprime(n) ; if isA136152(p+1) then print(p+1) ; fi ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 20 2008
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CROSSREFS
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Cf. A136151 A136153 A136154 A136155.
Adjacent sequences: A136149 A136150 A136151 this_sequence A136153 A136154 A136155
Sequence in context: A000977 A033992 A091454 this_sequence A090815 A093599 A007304
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KEYWORD
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easy,nonn
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net), Dec 16 2007
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EXTENSIONS
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Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 20 2008
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