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A236169 Numbers n such that n!*3^n + 1 is prime. 1
0, 2, 3, 8, 13, 19, 124, 199, 288, 359, 692, 3610, 5316, 5372, 7442, 8251, 14288, 16883, 17131 (list; graph; refs; listen; history; text; internal format)
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: A193882 A168343 A217330 * 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

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Last modified October 14 16:40 EDT 2019. Contains 328022 sequences. (Running on oeis4.)