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Primes of the form k!*3^k - 1.
1

%I #8 Feb 26 2018 18:58:28

%S 2,17,254561089305599,8483004771271882804592639999,

%T 706526001186582385898210420541078864497278132689882316799999999,

%U 353401447088718405944982176443380974931403135679741865504466985287679999999999

%N Primes of the form k!*3^k - 1.

%H Robert Price, <a href="/A290189/b290189.txt">Table of n, a(n) for n = 1..7</a>

%H Joe McLean, <a href="http://web.araachive.org/web/20091027034731/http://uk.geocities.com/nassarawa%40btinternet.com/probprim2.htm">Interesting Sources of Probable Primes</a>

%H OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>

%t Select[Table[k!*3^k - 1, {k, 0, 100}], PrimeQ[#]&]

%Y Cf. A121859.

%K nonn

%O 1,1

%A _Robert Price_, Jul 23 2017