A247467 Numbers n such that n!3 + 3^6 is prime.

4, 5, 7, 8, 10, 11, 14, 17, 35, 41, 50, 59, 89, 136, 164, 205, 224, 283, 763, 1034, 1253, 1630, 1820, 3199, 3800, 5080, 6124, 17306, 17398, 20768, 34033, 43607

Offset: 1

Author

Robert Price, Sep 17 2014

Keywords

• nonn
• more

Comments

Large terms correspond to probable primes.

a(33) > 50000.

Examples

			11!3+729 = 11*8*5*2+729 = 1609 is prime, so 11 is in the sequence.
		

Links

• Henri & Renaud Lifchitz, PRP Records. Search for n!3+729
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester
• Eric Weisstein's World of Mathematics, Multifactorial

Crossrefs

Cf. A007661, A037082, A084438, A243078.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, If[n < k + 1, n, n*MultiFactorial[n - k, k]]];
lst={};Do[If[PrimeQ[MultiFactorial[n, 3] + 729], AppendTo[lst, n]], {n, 100}];lst