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A288880 Primes of the form k!3 + 3^4, where k!3 is the triple factorial number (A007661).

%I A288880 #12 Apr 14 2025 05:34:33
%S A288880 83,109,12401,58321,24344401,96342481,2504902481,26582634158080081,
%T A288880 1143053268797440081,262134882788466688081,
%U A288880 427380210218181008588800081,142299187144047333874073600081,7825229077844441903818866688000081
%N A288880 Primes of the form k!3 + 3^4, where k!3 is the triple factorial number (A007661).
%H A288880 Robert Price, <a href="/A288880/b288880.txt">Table of n, a(n) for n = 1..16</a>
%H A288880 Henri and 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 A288880 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 A288880 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>.
%F A288880 a(n) = 81 + A007661(A247866(n)). - _Elmo R. Oliveira_, Apr 13 2025
%t A288880 MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
%t A288880 Select[Table[MultiFactorial[i, 3] + 3^4, {i, 0, 100}], PrimeQ[#]&]
%t A288880 Select[Table[Times@@Range[n,1,-3]+81,{n,100}],PrimeQ] (* _Harvey P. Dale_, Aug 13 2021 *)
%Y A288880 Cf. A007661, A247866.
%K A288880 nonn
%O A288880 1,1
%A A288880 _Robert Price_, Jun 18 2017