A261145 Numbers n such that n!3 + 3^10 is prime, where n!3 = n!!! is a triple factorial number (A007661).

2, 4, 7, 11, 25, 38, 47, 94, 95, 155, 275, 277, 292, 299, 395, 409, 614, 1409, 1963, 3422, 5243, 5884, 5971, 8527, 10882, 13223, 16406, 20851, 28886

Offset

1,1

Comments

Corresponding primes are: 59051, 59053, 59077, 59929, 608667049, 3091650738235049, 262134882788466747049, ...

a(30) > 50000.

Terms > 47 correspond to probable primes.

Links

Table of n, a(n) for n=1..29.

Henri & Renaud Lifchitz, PRP Records. Search for n!3+59049.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

11!3 + 3^10 = 11*8*5*2 + 59049 = 59929 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]]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 3] + 3^10] &]

Prog

(PARI) for(n=1, 1e3, if(ispseudoprime(prod(i=0, floor((n-1)/3), n-3*i) + 3^10), print1(n, ", "))) \\ Altug Alkan, Nov 18 2015

Crossrefs

Cf. A007661, A037082, A084438, A123910, A242994.

Sequence in context: A084992 A360886 A304040 * A277339 A153555 A259588

Adjacent sequences: A261142 A261143 A261144 * A261146 A261147 A261148

Keyword

nonn,more

Author

Robert Price, Nov 18 2015

Status

approved