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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

Table of n, a(n) for n=1..7.

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.)