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 A261730 Values of n such that prime(n)! - n! + 1 is a prime number. 0
 1, 2, 8, 85, 308 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Inspired by A261457. Initial primes of the form prime(n)! - n! + 1 are 2, 5, 121645100408791681. LINKS Table of n, a(n) for n=1..5. 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 Adjacent sequences: A261727 A261728 A261729 * A261731 A261732 A261733 KEYWORD nonn,more AUTHOR Altug Alkan, Aug 30 2015 EXTENSIONS a(4)-a(5) from Giovanni Resta, Aug 30 2015 STATUS approved

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Last modified September 16 13:56 EDT 2024. Contains 375976 sequences. (Running on oeis4.)