A023522 Sum of exponents in prime-power factorization of p(n)*p(n-1) - 1.

1, 2, 2, 3, 2, 4, 3, 3, 4, 2, 3, 3, 2, 4, 4, 3, 3, 4, 4, 2, 4, 4, 3, 5, 4, 3, 5, 5, 3, 5, 3, 4, 2, 4, 3, 5, 4, 4, 6, 4, 3, 3, 3, 4, 3, 4, 5, 4, 4, 3, 3, 3, 4, 4, 5, 4, 4, 3, 5, 2, 3, 5, 3, 4, 6, 3, 4, 3, 3, 4, 3, 5, 8, 3, 4, 6, 8, 3, 6

Offset: 2

Author

Clark Kimberling

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 2..1000

Programs

Mathematica

PrimeOmega[Times@@#-1]&/@Partition[Prime[Range[80]],2,1] (* Harvey P. Dale, Nov 22 2014 *)

PARI

a(n) = bigomega(prime(n)*prime(n-1) - 1); \\ Michel Marcus, Sep 30 2013

Formula

a(n) = A001222(A023515(n)). - Michel Marcus, Sep 30 2013

Extensions

Offset set to 2 and a(1) removed by Michel Marcus, Sep 30 2013