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Search: id:A135621
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| A135621 |
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Number of prime factors of 11^n + 2 (counted with multiplicity). |
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+0
1
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| 1, 1, 2, 2, 3, 1, 3, 3, 3, 1, 7, 3, 4, 3, 3, 2, 5, 2, 2, 3, 4, 3, 5, 3, 3, 3, 7, 3, 5, 6, 3, 2, 4, 3, 7, 5, 7, 3, 6, 3, 4, 4, 7, 4, 6, 7, 4, 2, 5, 3, 7, 5, 8, 4, 3, 4, 3, 5, 7, 6, 2, 5, 2, 5, 5, 4, 7, 7
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OFFSET
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0,3
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COMMENT
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a(n)=1 for n=0,1,5,9,287,8273, see A109076.
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EXAMPLE
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a(0)=1 because 11^0+2=3(prime),
a(1)=1 because 11^1+2=13(prime),
a(2)=2 because 11^2+2=123=3*41(semiprime),
a(3)=2 because 11^3+2=123=31*43(semiprime),
a(4)=3 because 11^4+2=14643=3^2*1627(3 prime factors).
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CROSSREFS
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Cf. A109076.
Sequence in context: A088741 A004595 A071681 this_sequence A077268 A162911 A131821
Adjacent sequences: A135618 A135619 A135620 this_sequence A135622 A135623 A135624
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Mar 03 2008
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