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Search: id:A104413
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| A104413 |
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Number of prime factors, with multiplicity, of the hexanacci numbers A001592. |
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+0
4
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| 0, 0, 1, 2, 3, 4, 5, 3, 3, 4, 4, 5, 6, 10, 2, 2, 7, 5, 8, 7, 10, 3, 2, 6, 6, 6, 7, 11, 2, 5, 3, 4
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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I am using a(-4)=a(-3)=a(-2)=a(-1)=a(0)=0, a(1)=1 here. Prime hexanacci numbers: a(3) = 1, ... [what is the next?], Semiprime hexanacci numbers: a(4) = 4 = 2^2, a(15) = 7617 = 3 * 2539, a(16) = 15109 = 29 * 521, a(23) = 1825529 = 337 * 5417, a(29) = 111196417 = 19 * 5852443.
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FORMULA
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a(n) = A001222(A001592(n)). a(n) = bigomega(A001592(n)).
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EXAMPLE
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a(1)=a(2)=0 because the first two nonzero hexanacci numbers are both 1, which has zero prime divisors.
a(3)=1 because the 3rd nonzero hexanacci number is 2, a prime, with only one prime divisor.
a(4)=2 because the 4th nonzero pentanacci number is 4 = 2^2 which has (with multiplicity) 2 prime divisors (which happen to be equal).
a(5)=3 because the 5th nonzero pentanacci number is 8 = 2^3.
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CROSSREFS
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Cf. A001591, A001222, A104411, A104412.
Sequence in context: A066296 A053626 A134364 this_sequence A127064 A117607 A088492
Adjacent sequences: A104410 A104411 A104412 this_sequence A104414 A104415 A104416
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Mar 06 2005
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