A247466 Numbers n such that n!3 - 3^6 is prime.

11, 26, 37, 38, 40, 41, 62, 131, 211, 212, 251, 272, 284, 383, 427, 538, 590, 860, 1087, 1280, 1826, 1835, 1895, 2276, 2524, 2872, 3769, 3878, 4334, 5704, 14332, 23386, 42694

Offset: 1

Author

Robert Price, Sep 17 2014

Keywords

• nonn
• more

Comments

Large terms correspond to probable primes.

a(34) > 50000.

Examples

			11!3-729 = 11*8*5*2-729= 151 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