A064186 Numbers n such that n!+1 and n!-1 have the same number of prime divisors (with repetition).

3, 5, 8, 9, 10, 13, 17, 20, 22, 24, 26, 34, 39, 53, 59, 61, 63, 69, 70, 76, 80, 87, 97, 99, 103, 124, 130

Offset

1,1

Comments

200, 236, 392 and 634 are terms. - Chai Wah Wu, Jan 03 2020

Links

Table of n, a(n) for n=1..27.

Mathematica

Select[Range[30], PrimeOmega[#! - 1] == PrimeOmega[#! + 1] &] (* Amiram Eldar, Dec 01 2019 *)

Prog

(PARI) for(n=2, 100, if(bigomega(n!+1)==bigomega(n!-1), print(n)))

Crossrefs

Cf. A054990, A054991.

Sequence in context: A191931 A325413 A328066 * A271048 A366473 A189127

Adjacent sequences: A064183 A064184 A064185 * A064187 A064188 A064189

Keyword

more,nonn

Author

Jason Earls, Sep 20 2001

Extensions

a(15)-a(25) from Donovan Johnson, Mar 09 2008

Offset corrected by Donovan Johnson, Jul 11 2013

a(26)-a(27) from Amiram Eldar, Dec 01 2019

Status

approved