A125174 Primes of the form k! + (k+1)! - 1.

2, 7, 29, 839, 3991679, 93405311999, 1394852659199, 6758061133823999, 315777214062132212662271999999, 9146650338351415815045119999999, 303916116658416027343136804044799999999, 836313165329095177704251551336018791628799999999

Offset: 1

Author

Tomas Xordan, Jan 12 2007

Keywords

• nonn

Comments

Next term is too long (167 digits) to include in data. - James C. McMahon, Dec 11 2024

Examples

			0!+1!-1 = 1 is not prime, 1!+2!-1 = 2 is prime, 2!+3!-1 = 7 is prime, 3!+4!-1 = 29 is prime, 4!+5!-1 = 143 = 11*13 is not prime.
		

Crossrefs

Cf. A087146 (values of k), A118913 (primes of the form k! + (k+1)! + 1).

Programs

Mathematica

Select[Table[n!+(n+1)!-1,{n,110}],PrimeQ] (* James C. McMahon, Dec 11 2024 *)

PARI

for(n=0,35,if(isprime(a=n!+(n+1)!-1),print1(a,",")))

Extensions

Edited and extended by Klaus Brockhaus, Jan 24 2007

a(12) from James C. McMahon, Dec 11 2024