A289755 - OEIS

A289755

Primes of the form k!9-1, where k!9 is the nonuple factorial number (A114806).

%I #11 Sep 12 2019 09:32:23

%S 2,3,5,7,89,439,1609,4373,22679,5445439,152681759,17893715839,

%T 101636305971199,12652843234348799,266565181393279999,

%U 4929089879840974847999,16401565050020468398079999,2263415976902824638935039999,1692607074564424130419507199999

%N Primes of the form k!9-1, where k!9 is the nonuple factorial number (A114806).

%H Harvey P. Dale, <a href="/A289755/b289755.txt">Table of n, a(n) for n = 1..41</a> (* Terms 1 through 33 from Robert Price *)

%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n9-1&action=Search">PRP Records.Search for n!9-1.</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, 9] - 1, {i, 2, 100}], PrimeQ[#]&]

%t Select[Table[Times@@Range[n,1,-9]-1,{n,200}],PrimeQ] (* _Harvey P. Dale_, Sep 12 2019 *)

%Y Cf. A204659.

%K nonn

%O 1,1

%A _Robert Price_, Jul 11 2017