OFFSET
1,4
EXAMPLE
The only binary 5-digit (-bit) primes are decimal 17, 19, 23, 29 and 31; and reading the binary representations of these as base-3 representations instead produces numbers whose decimal representations are 82, 85, 94, 118 and 121. None of these 5 numbers are prime, so a(5)=0.
PROG
(PARI)
{
i=1; while(1,
z=0; forprime(p=2^(i-1), 2^i-1,
b=binary(p); u=0; for(j=1, i,
if(b[j], u+=3^(i-j))); if(isprime(u), z++));
print1(z", "); i++)
}
CROSSREFS
KEYWORD
nonn,base
AUTHOR
James G. Merickel, May 31 2014
STATUS
approved