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A118144 Numbers of prime factors of l, where l is defined in A118534. 2
0, 0, 1, 0, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 1, 1, 2, 2, 3, 2, 1, 3, 2, 4, 2, 3, 3, 3, 3, 3, 2, 3, 4, 2, 3, 2, 1, 2, 2, 1, 2, 3, 4, 4, 3, 2, 1, 2, 4, 4, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

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 l, largest l such that prime(n+1) = prime(n) + (prime(n) mod l), or 0 if no such l exists.

EXAMPLE

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

for a(3), l=3 thus a(3)=1,

for a(8), l=15=3*5 thus a(8)=2,

for a(24), l=81=3*3*3*3 thus a(24)=4.

CROSSREFS

Cf. A118534, A117563, A118123, A117078.

Sequence in context: A192056 A207385 A306242 * A136691 A231168 A276830

Adjacent sequences:  A118141 A118142 A118143 * A118145 A118146 A118147

KEYWORD

nonn

AUTHOR

Rémi Eismann and Fabien Sibenaler, May 14 2006, Feb 14 2008

STATUS

approved

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Last modified June 15 17:43 EDT 2019. Contains 324142 sequences. (Running on oeis4.)