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A288717 Primes of the form k!7+1, where k!7 is the septuple factorial number (A114799). 1

%I #7 Dec 23 2022 18:46:13

%S 2,3,5,7,19,31,61,79,12241,19801,29641,76561,379441,2016841,2756161,

%T 1838865601,4150656721,337767408001,956960801281,21617114112001,

%U 1534815101952001,9590944392057601,30891838760640001,119715577952256001,767275551364608001

%N Primes of the form k!7+1, where k!7 is the septuple factorial number (A114799).

%H Robert Price, <a href="/A288717/b288717.txt">Table of n, a(n) for n = 1..46</a>

%H Henri& Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n7+1&amp;action=Search">PRP Records.Search for n!7+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, 7] + 1, {i, 0, 100}], PrimeQ[#]&]

%t Select[Table[Times@@Range[n,1,-7]+1,{n,100}],PrimeQ] (* _Harvey P. Dale_, Dec 23 2022 *)

%Y Cf. A156165.

%K nonn

%O 1,1

%A _Robert Price_, Jun 13 2017

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Last modified April 18 22:18 EDT 2024. Contains 371782 sequences. (Running on oeis4.)