

A165210


Primes of the form (6^m  1)/5.


5




OFFSET

1,1


COMMENTS

Prime repunits in base 6 whose representation consists of m 1's. The exponents m are in A004062. a(5) and a(6) have 55 and 99 decimal digits, respectively.


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..9


FORMULA

a(n) = (6^A004062(n)  1)/5.


EXAMPLE

a(2) = (6^A004062(2)  1)/5 = (6^3  1)/5 = 215/5 = 43, which is 111_6.


MATHEMATICA

Select[Table[(6^n1)/5, {n, 0, 2000}], PrimeQ] (* Vincenzo Librandi, Dec 09 2011 *)


PROG

(Magma) [a: n in [1..200]  IsPrime(a) where a is (6^n1) div 5 ]; // Vincenzo Librandi, Dec 09 2011


CROSSREFS

Cf. A004062, A003464, A085104, A000668, A076481, A086122, A102170, A004022.
Sequence in context: A177507 A258182 A048605 * A162454 A203210 A323923
Adjacent sequences: A165207 A165208 A165209 * A165211 A165212 A165213


KEYWORD

nonn


AUTHOR

Rick L. Shepherd, Sep 07 2009


STATUS

approved



