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

1,1

Comments

Large terms correspond to probable primes.

a(34) > 50000.

Links

Table of n, a(n) for n=1..33.

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

Example

11!3-729 = 11*8*5*2-729= 151 is prime, so 11 is in the sequence.

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

Crossrefs

Cf. A007661, A037082, A084438, A243078.

Sequence in context: A316315 A251268 A174223 * A329809 A190684 A354383

Adjacent sequences: A247463 A247464 A247465 * A247467 A247468 A247469

Keyword

nonn,more

Author

Robert Price, Sep 17 2014

Status

approved