cp's OEIS Frontend

A289855 Primes of the form k!2 - 128, where k!2 is the double factorial number (A006882).

%I A289855 #10 Apr 15 2025 08:27:43
%S A289855 10267,135007,13749310447,1192568192774434123539907640497,
%T A289855 29215606371473169285018060091249259296747,
%U A289855 1009847364737869270905302433221592504062302663202724609247,34720596058582394465875230149026168047833371128291024141249287753332469144201839599609247
%N A289855 Primes of the form k!2 - 128, where k!2 is the double factorial number (A006882).
%H A289855 Robert Price, <a href="/A289855/b289855.txt">Table of n, a(n) for n = 1..10</a>
%H A289855 Henri and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n2-128&amp;action=Search">PRP Records.Search for n!2-128</a>.
%H A289855 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 A289855 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>.
%F A289855 a(n) = A006882(A257864(n)) - 128. - _Elmo R. Oliveira_, Apr 14 2025
%t A289855 MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
%t A289855 Select[Table[MultiFactorial[i, 2] - 128, {i, 8, 100}], PrimeQ[#]&]
%t A289855 Select[Range[8,120]!!-128,PrimeQ] (* _Harvey P. Dale_, Dec 01 2018 *)
%Y A289855 Cf. A006882, A257864.
%K A289855 nonn
%O A289855 1,1
%A A289855 _Robert Price_, Jul 13 2017