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%I #59 Apr 17 2023 02:09:52
%S 0,3,8,13,19,423,585,2746,2855
%N Numbers k such that (2*k)! + k! + 1 is prime.
%e 0! + 0! + 1 = 3 is prime.
%e 6! + 3! + 1 = 727 is prime.
%p select(k->isprime(factorial(2*k)+factorial(k)+1),[$0..600]); # _Muniru A Asiru_, May 27 2018
%t Flatten[{0, Select[Range[100], PrimeQ[(2*#)! + #! + 1] &]}] (* _Vaclav Kotesovec_, Mar 25 2018 *)
%o (PARI) isok(k) = ispseudoprime((2*k)!+k!+1); \\ _Altug Alkan_, Mar 22 2018
%Y A300947 gives the primes.
%Y Cf. A002981, A237443.
%K nonn,more
%O 1,2
%A _Seiichi Manyama_, Mar 22 2018
%E a(8)-a(9) from _Michael S. Branicky_, Apr 16 2023
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