

A109387


Numbers k such that 3^k  k^3 is prime.


11



1, 4, 10, 52, 112, 212, 346, 406, 512, 13904, 76610, 89746, 114892
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OFFSET

1,2


COMMENTS

Terms <= 512 correspond to certified primes. Next term after 13904 is greater than 20000.


LINKS



EXAMPLE

4 is a term because 3^4  4^3 = 17 is prime.
3^10  10^3 = 58049 is prime, hence 10 is a term.


MATHEMATICA

Do[If[PrimeQ[3^n  n^3], Print[n]], {n, 1, 20000}]


PROG



CROSSREFS



KEYWORD

hard,more,nonn


AUTHOR



EXTENSIONS

a(13) from Norbert Schneider submitted by Robert Price, Mar 16 2019


STATUS

approved



