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A051857 Numbers n such that (n!)^2-n!+1 is prime. 0
2, 3, 5, 7, 38, 2319, 2996, 3321, 3892 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

Table of n, a(n) for n=1..9.

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.

PROG

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

CROSSREFS

Cf. A002981, A002982, A046029, A051856.

Sequence in context: A202263 A153014 A100891 * A050654 A215157 A110363

Adjacent sequences:  A051854 A051855 A051856 * A051858 A051859 A051860

KEYWORD

nonn,hard,more

AUTHOR

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

EXTENSIONS

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

STATUS

approved

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Last modified January 21 04:53 EST 2020. Contains 331104 sequences. (Running on oeis4.)