A079294 Number of distinct prime factors of the numerator of the 2n-th Bernoulli number.

0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 2, 2, 3, 3, 3, 2, 1, 2, 2, 1, 5, 3, 3, 3, 5, 3, 4, 5, 3, 5, 2, 3, 6, 5, 2, 2, 3, 4, 5, 4, 5, 4, 4, 4, 4, 6, 5, 6, 5, 7, 5, 5, 3, 6, 4, 2, 5, 2, 3, 4, 9, 4, 6, 7, 4, 5, 4, 8, 8, 4, 2, 7, 7, 7, 7, 8, 5, 8, 6, 5, 8, 9, 6, 5, 3, 8

Offset: 0

Author

Benoit Cloitre, Feb 09 2003

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 0..103
• S. S. Wagstaff, Jr., Factors of Bernoulli numbers

Crossrefs

Cf. A001221, A000367, A046886.

Programs

Mathematica

Table[PrimeNu[Numerator[BernoulliB[2n]]], {n, 0, 30}] (* Amiram Eldar, Feb 09 2020 *)

PARI

a(n)=omega(numerator(bernfrac(2*n)))

Formula

a(n) = A001221(abs(A000367(n))). - Amiram Eldar, Feb 09 2020

Extensions

More terms from T. D. Noe, Feb 13 2004