A176038 Primes of the form k!*(k+1)! - 1 or k!*(k+1)! + 1.

2, 3, 11, 13, 2879, 86399, 114000816848279961600001, 2284848632399058501374484565150666260597460935294482959564800000000000001

Offset: 1

Author

Jonathan Vos Post, Apr 07 2010

Keywords

• more
• nonn

Comments

Primes of the form A010790(k)-1 or A010790(k)+1. This is the 2nd sequence in the supersequence whose first member is factorial primes, A002981 UNION A002982. No more through 20!*(20+1)! + 1.

a(9) has already 225 digits. The terms are generated by n= 0,1,2,2,4,5,14,32,76,166... [From R. J. Mathar, Aug 31 2010]

Examples

			a(6) = 86399 because 5!*(5+1)! - 1 = 86399 is prime. a(7) = 114000816848279961600001 because 14!*(14+1)! + 1 = 114000816848279961600001 is prime.
		

Crossrefs

Cf. A000040, A000142, A002981, A002982, A010790.

Formula

[{A010790(n)-1} INTERSECTION A000040] UNION [{A010790(n)+1} INTERSECTION A000040].

Extensions

One more term from R. J. Mathar, Aug 31 2010