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Primes in A290044.
0

%I #14 Jul 24 2017 11:57:31

%S 7,41,176075177,49127973630377

%N Primes in A290044.

%C For n < 20, A290044(n) are prime when n = {2, 3, 9, 13}.

%C For n >= 20, 19|A290044(n). Therefore there are only 4 terms in this sequence.

%e 41 = |0!! - 2!! + 4!! - 6!!| is prime.

%t Select[Table[Abs@ Sum[(-1)^k*(2 k)!!, {k, 0, n}], {n, 0, 60}], PrimeQ] (* _Michael De Vlieger_, Jul 19 2017 *)

%Y Cf. A006882, A071828, A290044.

%K nonn,fini,full

%O 1,1

%A _XU Pingya_, Jul 19 2017