cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A051592 Numbers k such that k!!!!!! - 1 is prime.

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%I A051592 #24 May 31 2024 20:43:36
%S A051592 3,4,6,12,14,54,74,102,114,302,318,366,614,1178,1188,3110,7284,21432,
%T A051592 21906,25848,29882,38618,41990,84510,86022
%N A051592 Numbers k such that k!!!!!! - 1 is prime.
%C A051592 k!!!!!! = k*(k-6)*(k-12)*(k-18)*...
%C A051592 The search for multifactorial primes started by Ray Ballinger is now continued by a team of volunteers on the website of Ken Davis (see link).
%H A051592 Ray Ballinger, <a href="http://web.archive.org/web/20160604135248/http://www.prothsearch.net/multifac.html">Status of Search for Multifactorial Primes</a>.
%H A051592 Ken Davis, <a href="http://mfprimes.free-dc.org">Status of Search for Multifactorial Primes</a>.
%H A051592 Ken Davis, <a href="http://mfprimes.free-dc.org/mfdata/f06m.html">Results for n!6-1.</a>.
%t A051592 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
%t A051592 Select[Range[0, 1000], PrimeQ[MultiFactorial[#, 6] - 1] & ] (* _Robert Price_, Apr 19 2019 *)
%Y A051592 Cf. A085158 (sextuple factorials), A085150.
%K A051592 hard,nonn
%O A051592 1,1
%A A051592 _N. J. A. Sloane_
%E A051592 Edited and extended by _Hugo Pfoertner_, Jun 23 2003
%E A051592 Corrected and extended by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008