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A204662 Numbers n such that n!8-1 is prime. 8

%I

%S 3,4,6,8,10,12,14,16,18,22,28,30,42,48,58,68,80,86,92,108,110,112,130,

%T 198,220,230,322,432,460,478,686,706,714,842,950,1010,1090,1314,1904,

%U 2264,2804,3164,3324,4740,4824,4918,5086,5442,6994,7898,8236,8684,10088,13990,15320,17570,18218,21564,22198,22684,24314,24780,25790,38726

%N Numbers n such that n!8-1 is prime.

%C n!8 = A114800(n).

%C No other terms < 50000. - _Robert Price_, Aug 15 2012

%H Ken Davis, <a href="http://mfprimes.free-dc.org">Status of Search for Multifactorial Primes</a>.

%H Ken Davis, <a href="http://mfprimes.free-dc.org/mfdata/f08m.html">Results for n!8-1.</a>

%t MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];

%t Select[Range[0, 1000], PrimeQ[MultiFactorial[#, 8] - 1] & ] (* _Robert Price_, Apr 19 2019 *)

%o (PARI) for(n=0,9999,isprime(prod(i=0,(n-2)\8,n-8*i)-1)& print1(n","))

%Y Cf. A204657, A204658, A204659, A204660, A204661, A204663, A204664, A156165, A156167, A085150, A085148, A085146, A037083, A080778, A002981.

%K nonn,hard

%O 1,1

%A _M. F. Hasler_, Jan 17 2012

%E a(39)-a(64) from _Robert Price_, Aug 15 2012

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Last modified April 18 15:08 EDT 2021. Contains 343089 sequences. (Running on oeis4.)