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A106752 Numbers of prime factors of k, k defined in A117078. +0
1
0, 0, 1, 0, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; graph; listen)
OFFSET

1,6

COMMENT

a(n) = 0 only for n = 1, 2 and 4.

LINKS

Remi Eismann, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = numbers of factors of A117078(n). A117078(n) : smallest k such that prime(n+1) = prime(n) + (prime(n) mod k), or 0 if no such k exists.

EXAMPLE

For a(1), k=0 thus a(1)=0,

For a(3), k=3 thus a(3)=1,

For a(11), k=25=5*5 thus a(11)=2.

CROSSREFS

Cf. A117078, A117563, A118534, A118144, A118123.

Sequence in context: A128184 A025450 A139128 this_sequence A136441 A030561 A074064

Adjacent sequences: A106749 A106750 A106751 this_sequence A106753 A106754 A106755

KEYWORD

nonn

AUTHOR

Remi Eismann (reismann(AT)free.fr), Jun 22 2007, Feb 14 2008

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Last modified November 27 14:50 EST 2009. Contains 167570 sequences.


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