A064186 - OEIS

%I #19 Jan 03 2020 21:19:19

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

%T 103,124,130

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

%C 200, 236, 392 and 634 are terms. - _Chai Wah Wu_, Jan 03 2020

%t Select[Range[30], PrimeOmega[#! - 1] == PrimeOmega[#! + 1] &] (* _Amiram Eldar_, Dec 01 2019 *)

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

%Y Cf. A054990, A054991.

%K more,nonn

%O 1,1

%A _Jason Earls_, Sep 20 2001

%E a(15)-a(25) from _Donovan Johnson_, Mar 09 2008

%E Offset corrected by _Donovan Johnson_, Jul 11 2013

%E a(26)-a(27) from _Amiram Eldar_, Dec 01 2019