A236169 Numbers n such that n!*3^n + 1 is prime.

0, 2, 3, 8, 13, 19, 124, 199, 288, 359, 692, 3610, 5316, 5372, 7442, 8251, 14288, 16883, 17131

Offset

1,2

Comments

a(20) > 25000.

Corresponding primes are all verified prime (i.e., not probable prime): 2, 19, 163, 264539521, 9927882482918401, 141383412854531380076544001, ...

Links

Table of n, a(n) for n=1..19.

Mathematica

Do[f=n!*3^n+1; If[PrimeQ[f], Print[{n, f}]], {n, 0, 25000}]

Prog

(PARI) isok(n) = isprime(n!*3^n + 1); \\ Michel Marcus, Jul 23 2017

Crossrefs

Cf. A091415, A002982, A121859.

Sequence in context: A168343 A217330 A358207 * A080478 A002053 A102315

Adjacent sequences: A236166 A236167 A236168 * A236170 A236171 A236172

Keyword

nonn,more

Author

Robert Price, Jan 19 2014

Extensions

a(1)=0 prepended by Robert Price, Jul 22 2017

Status

approved