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A325204
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Numbers k such that k*(k+1)*(k+2) has exactly 4 distinct prime factors.
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3
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5, 9, 10, 11, 12, 14, 15, 17, 18, 22, 23, 24, 25, 26, 27, 30, 31, 32, 36, 46, 47, 48, 52, 62, 71, 72, 79, 80, 81, 96, 106, 107, 126, 127, 162, 191, 192, 241, 242, 256, 382, 431, 486, 512, 576, 862, 1151, 1152, 2186, 2591, 2592, 2916, 4372, 8191, 8746, 131071, 131072, 139967, 472391, 524287, 786431, 995326, 995327
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OFFSET
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1,1
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COMMENTS
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Contains 2^p-1 for p in A107360 except 3.
Contains all terms of A325255 except 2 and 4.
Contains k-1 for k in A027856 except 4.
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LINKS
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EXAMPLE
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a(3)=10 is in the sequence because 10*11*12 has four distinct prime factors: 2, 3, 5, 11.
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MAPLE
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select(t -> nops(numtheory:-factorset(t) union numtheory:-factorset(t+1) union numtheory:-factorset(t+2))=4, [$1..10^6]);
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PROG
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(PARI) select(k->4==omega(k*(k+1)*(k+2)), [1..10000]) \\ Andrew Howroyd, Sep 05 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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