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Search: id:A163109
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| 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 4, 1, 2, 1, 2, 2, 2, 1, 4, 2, 2, 2, 2, 1, 4, 1, 2, 2, 2, 2, 6, 1, 2, 2, 4, 1, 4, 1, 2, 2, 2, 1, 4, 2, 2
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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a(n) = A000010(A000005(n)) - Charles R Greathouse IV Aug 11 2009
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FORMULA
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a(1) = 1, a(p) = 1 for p = primes (A000040), a(pq) = 2 for pq = product of two distinct primes (A006881), a(pq...z) = 2^(k-1) for pq...z = product of k (k > 2) distinct primes p, q, ..., z (A120944), a(p^(q-1) = q - 1 for p, q = primes (A000040).
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EXAMPLE
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a(16) = a(2^(5-1)) = 5-1 = 4 (2 and 5 are primes).
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CROSSREFS
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Sequence in context: A082477 A036430 A163377 this_sequence A128428 A056171 A076755
Adjacent sequences: A163106 A163107 A163108 this_sequence A163110 A163111 A163112
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KEYWORD
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nonn,easy
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AUTHOR
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Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Jul 20 2009
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