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A289850 Primes of the form k!2 - 4, where k!2 is the double factorial number (A006882).

%I A289850 #10 Apr 14 2025 12:27:13
%S A289850 11,101,941,10391,135131,2027021,654729071,7905853580621,
%T A289850 221643095476699771871,
%U A289850 79777941814291672401518892224505807820921910393015244140621,6462013286957625464523030270184970433494674741834234775390621
%N A289850 Primes of the form k!2 - 4, where k!2 is the double factorial number (A006882).
%H A289850 Robert Price, <a href="/A289850/b289850.txt">Table of n, a(n) for n = 1..13</a>
%H A289850 Henri and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n2-4&amp;action=Search">PRP Records.Search for n!2-4</a>.
%H A289850 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 A289850 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>.
%F A289850 a(n) = A006882(A123910(n)) - 4. - _Elmo R. Oliveira_, Apr 14 2025
%t A289850 MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
%t A289850 Select[Table[MultiFactorial[i, 2] - 4, {i, 4, 100}], PrimeQ[#]&]
%t A289850 Select[Range[4,100]!!-4,PrimeQ] (* _Harvey P. Dale_, Dec 16 2020 *)
%Y A289850 Cf. A006882, A123910.
%K A289850 nonn
%O A289850 1,1
%A A289850 _Robert Price_, Jul 13 2017