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A086598 Number of distinct prime factors in Lucas(n). +0
3
0, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 3, 1, 2, 3, 1, 1, 3, 1, 2, 3, 3, 2, 3, 3, 2, 3, 2, 2, 4, 1, 2, 3, 3, 4, 4, 1, 2, 4, 3, 1, 5, 2, 4, 6, 3, 1, 4, 2, 4, 4, 3, 1, 4, 4, 2, 4, 3, 3, 6, 1, 2, 6, 2, 5, 5, 2, 2, 5, 4, 1, 4, 2, 3, 7, 2, 4, 4, 1, 2, 5, 4, 2, 6, 4, 2, 5, 3, 2, 6, 3, 3, 4, 4, 5, 4, 2, 4, 7, 4, 3, 6, 3, 4, 9 (list; graph; listen)
OFFSET

1,6

COMMENT

Interestingly, the Lucas numbers separate the primes into three disjoint sets: (A053028) primes that do not divide any Lucas number, (A053027) primes that divide Lucas numbers of even index and (A053032) primes that divide Lucas numbers of odd index.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000 (using Blair Kelly's data)

Blair Kelly, Fibonacci and Lucas Factorizations

Eric Weisstein's World of Mathematics, Lucas Number

FORMULA

a(n) = Sum{d|n and n/d odd} A086600(d) + 1 if 6|n, a Mobius-like transform

MATHEMATICA

Lucas[n_] := Fibonacci[n+1] + Fibonacci[n-1]; Table[Length[FactorInteger[Lucas[n]]], {n, 150}]

CROSSREFS

Cf. A000204 (Lucas numbers), A086599 (number of prime factors, counting multiplicity), A086600 (number of primitive prime factors).

Cf. A053027, A053028, A053032.

Sequence in context: A035170 A111949 A143323 this_sequence A074746 A133188 A008612

Adjacent sequences: A086595 A086596 A086597 this_sequence A086599 A086600 A086601

KEYWORD

hard,nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Jul 24 2003

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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