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Primes of the form k!3 + 3^4, where k!3 is the triple factorial number (A007661).
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%I #7 Aug 13 2021 15:03:21

%S 83,109,12401,58321,24344401,96342481,2504902481,26582634158080081,

%T 1143053268797440081,262134882788466688081,

%U 427380210218181008588800081,142299187144047333874073600081,7825229077844441903818866688000081

%N Primes of the form k!3 + 3^4, where k!3 is the triple factorial number (A007661).

%H Robert Price, <a href="/A288880/b288880.txt">Table of n, a(n) for n = 1..16</a>

%H Henri& Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n3+3^4&amp;action=Search">PRP Records.Search for n!3+3^4.</a>

%H Joe McLean, <a href="http://web.archive.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 MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];

%t Select[Table[MultiFactorial[i, 3] + 3^4, {i, 0, 100}], PrimeQ[#]&]

%t Select[Table[Times@@Range[n,1,-3]+81,{n,100}],PrimeQ] (* _Harvey P. Dale_, Aug 13 2021 *)

%Y Cf. A247866.

%K nonn

%O 1,1

%A _Robert Price_, Jun 18 2017