

A109887


Numbers n such that 3^n + phi(n) is prime.


0



3, 4, 10, 20, 44, 60, 583, 677, 947, 1182, 12048, 16018, 74316
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OFFSET

1,1


COMMENTS

All terms correspond to certified primes (Primo 2.2.0 beta). No more terms through 10000.
a(14) > 10^5. [From Donovan Johnson, Feb 06 2010]


LINKS

Table of n, a(n) for n=1..13.


MATHEMATICA

Do[If[PrimeQ[3^n + EulerPhi[n]], Print[n]], {n, 1, 10000}]


CROSSREFS

Sequence in context: A036649 A255539 A321197 * A200981 A266729 A103038
Adjacent sequences: A109884 A109885 A109886 * A109888 A109889 A109890


KEYWORD

hard,nonn


AUTHOR

Ryan Propper, Aug 31 2005


EXTENSIONS

a(11)a(13) from Donovan Johnson, Feb 06 2010


STATUS

approved



