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A124874
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Number of primes dividing A007408(n).
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0
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0, 1, 1, 3, 2, 3, 3, 2, 3, 4, 3, 2, 3, 2, 1, 3, 2, 4, 1, 3, 2, 5, 2, 4, 2, 1, 3, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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EXAMPLE
| a(1) = 0 since no prime divides A007408(1)=1,
a(2) = 1 since 3 is the only prime dividing A007408(2)=9,
a(3) = 1 since A007408(3)=251 is prime,
a(4) = 3 since A007408(4)=5 x 11 x 37,
a(6) = 3 since 7,11,53 are the only primes dividing A007408(6)=7^2 x 11 x 53.
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MAPLE
| seq( (nops@op)(2, (ifactors@A007408)(n)), n=1..25);
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CROSSREFS
| Cf. A007408, A124876, A124877.
Sequence in context: A165601 A054263 A178775 * A016459 A060585 A114451
Adjacent sequences: A124871 A124872 A124873 * A124875 A124876 A124877
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KEYWORD
| hard,nonn
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AUTHOR
| M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 11 2006
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