OFFSET
1,1
COMMENTS
Koch snowflake primes. The values k such that a(n) = round(3*(4/3)^k) are: 0, 2, 3, 5, 6, 11, 34, 49, 64, 67, 68, 86, 135, 157, 277.
EXAMPLE
a(9) = round(3*(4/3)^49) = 3973007.
a(10) = round(3*(4/3)^64) = 297303757.
a(11) = round(3*(4/3)^67) = 704720017.
MAPLE
for k from 0 to 300 do
p := round(4^k/3^(k-1)) ;
if isprime(p) then
printf("%d, \n", p) ;
end if;
end do: # R. J. Mathar, Jun 30 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Jul 14 2013
STATUS
approved