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A261730
Values of n such that prime(n)! - n! + 1 is a prime number.
0
1, 2, 8, 85, 308
OFFSET
1,2
COMMENTS
Inspired by A261457.
Initial primes of the form prime(n)! - n! + 1 are 2, 5, 121645100408791681.
EXAMPLE
For n=1, prime(1)!-1!+1 = 2 is a prime number.
MATHEMATICA
Select[Range[400], PrimeQ[Prime[#]! - #! + 1] &] (* Vincenzo Librandi, Aug 31 2015 *)
PROG
(PARI) for(n=1, 1e3, if(isprime(prime(n)!-n!+1), print1(n", ")))
(Magma) [n: n in [1..80] | IsPrime(Factorial(NthPrime(n))-Factorial(n)+1)]; // Vincenzo Librandi, Aug 31 2015
CROSSREFS
Cf. A261457.
Sequence in context: A134089 A136647 A306001 * A052456 A276991 A000532
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Aug 30 2015
EXTENSIONS
a(4)-a(5) from Giovanni Resta, Aug 30 2015
STATUS
approved