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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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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
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OFFSET
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1,1
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LINKS
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FORMULA
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Find primes followed by N with exactly three prime factors, without repetition.
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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, Feb 20 2008
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MATHEMATICA
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Select[Prime[Range[110]]+1, PrimeNu[#]==3&] (* Harvey P. Dale, Apr 08 2012 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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