A106752 Numbers of prime factors of k, k defined in A117078.

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

Offset

1,6

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 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 * A136441 A030561 A202053

Adjacent sequences: A106749 A106750 A106751 * A106753 A106754 A106755

Keyword

nonn

Author

Rémi Eismann, Jun 22 2007, Feb 14 2008

Status

approved