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A177876
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a(n) is the number of distinct prime factors in Lucas-Lehmer numbers A003010(k-2)/(2^k-1), where k = A000043(n+1).
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1
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OFFSET
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1,1
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COMMENTS
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a(5) of this sequence will require the factorization of A003010(15), an 18742-digit integer divisible by 2^17-1.
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LINKS
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EXAMPLE
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a(1)=2 because A003010(1)=14, contains exactly 2 distinct prime factors;
a(2)=3 because A003010(3)=37634, contains exactly 3 distinct prime factors;
a(3)=3 because A003010(5)=2005956546822746114, contains exactly 3 distinct prime factors;
a(4)=4 because A003010(11)=the associated 1172-digit Lucas-Lehmer number, contains exactly 4 distinct prime factors.
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CROSSREFS
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KEYWORD
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nonn,hard,bref,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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