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Primes of the form (7+k!)/7.
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%I #41 Oct 14 2024 01:37:05

%S 5702401,186810624001,2988969984001,2215887149047283712000001,

%T 1476163995198020704238093048217600000001,

%U 19811874077955690819705574245769915192271839538955347505831613562880000000000001

%N Primes of the form (7+k!)/7.

%C For numbers k for which (7+k!)/7 is prime see A139065.

%H Amiram Eldar, <a href="/A139064/b139064.txt">Table of n, a(n) for n = 1..12</a>

%F a(n) = A139154(A139065(n)). - _Amiram Eldar_, Oct 14 2024

%t a = {}; Do[If[PrimeQ[(n! + 7)/7], AppendTo[a, (n! + 7)/7]], {n, 1, 50}]; a

%o (PARI) for(k=7,1e3,if(ispseudoprime(t=k!/7+1),print1(t", "))) \\ _Charles R Greathouse IV_, Jul 15 2011

%Y Cf. A020458, A082672, A089085, A089130, A117141, A007749, A139056, A139057, A139058, A139059, A139060, A139061, A139062, A139063, A139065, A139066, A139154.

%K nonn

%O 1,1

%A _Artur Jasinski_, Apr 07 2008