A066877 a(n) = omega(n!-1), where omega is the number of distinct primes dividing n, A001221.

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

Offset

1,5

Links

Amiram Eldar, Table of n, a(n) for n = 1..135

Hisanori Mishima, Appendix 1. Factorization results for n!-1

Mathematica

Table[ Length[ FactorInteger[ n! - 1]], {n, 1, 30}]

Crossrefs

Sequence in context: A117592 A117942 A290092 * A240071 A029255 A029272

Adjacent sequences: A066874 A066875 A066876 * A066878 A066879 A066880

Keyword

hard,nonn

Author

Robert G. Wilson v, Jan 21 2002

Extensions

a(52) corrected and more terms added by Amiram Eldar, Oct 03 2019

Status

approved