A051857 Numbers n such that (n!)^2-n!+1 is prime.

2, 3, 5, 7, 38, 2319, 2996, 3321, 3892

Offset: 1

Author

Andrew Walker (ajw01(AT)uow.edu.au), Dec 13 1999

Keywords

• nonn
• hard
• more

Comments

a(1)-a(9) are verified primes using BLS option in pfgw. - Robert Price, Aug 24 2014

a(10) > 15000. - Robert Price, Aug 24 2014

Links

• C. K. Caldwell, The Prime Pages
• C. Nash, Prime Form [?Broken link]
• M. Oakes, Re: Gaussian primorial and factorial primes, Primeform, Dec 21 2010
• Mike Oakes, Andrew Walker, David Broadhurst, Gaussian primorial and factorial primes, digest of 7 messages in primeform Yahoo group, Dec 20 - Dec 21, 2010.

Crossrefs

Cf. A002981, A002982, A046029, A051856.

Programs

PARI

isok(n) = isprime((n!)^2-n!+1); \\ Michel Marcus, Aug 26 2013

Extensions

a(7)-a(9) from Robert Price, Aug 24 2014