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 A242487 Numbers k such that (2*k)! + k! + 1 is prime. 3
 0, 3, 8, 13, 19, 423, 585 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Next term, if it exists, is greater than 5000. - Vaclav Kotesovec, Mar 25 2018 LINKS EXAMPLE 0! + 0! + 1 =   3 is prime. 6! + 3! + 1 = 727 is prime. MAPLE select(k->isprime(factorial(2*k)+factorial(k)+1), [\$0..600]); # Muniru A Asiru, May 27 2018 MATHEMATICA Flatten[{0, Select[Range[100], PrimeQ[(2*#)! + #! + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *) PROG (PARI) isok(k) = ispseudoprime((2*k)!+k!+1); \\ Altug Alkan, Mar 22 2018 CROSSREFS A300947 gives the primes. Cf. A002981, A237443. Sequence in context: A081989 A264780 A208276 * A303592 A120883 A317195 Adjacent sequences:  A242484 A242485 A242486 * A242488 A242489 A242490 KEYWORD nonn,more AUTHOR Seiichi Manyama, Mar 22 2018 STATUS approved

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Last modified October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)