OFFSET
1,3
COMMENTS
Corresponding primes of the form 10^n + 5^n + 2^n are {3, 17, 10078253, 10000000004656612873079540061773, 10000000000072759576141834396472156597, 100000000000000000000042351647362715016953416125036343281344004402684973, ...}
a(12) > 10000 if it exists. - Felix Fröhlich, Sep 17 2016
a(16) > 100000. - Robert Price, Dec 29 2016
MATHEMATICA
Do[f=10^n+5^n+2^n; If[PrimeQ[f], Print[{n, f}]], {n, 1, 2000}]
PROG
(PARI) is(n) = ispseudoprime(10^n+5^n+2^n) \\ Felix Fröhlich, Sep 17 2016
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
René Gy, Sep 16 2016
EXTENSIONS
a(11) from Felix Fröhlich, Sep 17 2016
a(12)-a(15) from Robert Price, Dec 29 2016
STATUS
approved