OFFSET
1,1
COMMENTS
Sequence is likely to be finite. If it exists, a(26) > 10^200. - Robert Israel, Jan 12 2017
EXAMPLE
37 is in the sequence because it is a prime and its binary expansion 100101 and ternary expansion 1101 both have exactly 3 ones.
131 is in the sequence because it is a prime and its binary expansion 10000011 and ternary expansion 11212 both have exactly 3 ones.
MAPLE
A:= NULL:
for a from 2 to 100 do
for b from 1 to a-1 do
p:= 2^a + 2^b + 1;
if numboccur(1, convert(p, base, 3)) = 3 and isprime(p) then
A:= A, p
fi
od od:
A; # Robert Israel, Jan 12 2017
MATHEMATICA
Select[Prime[Range[500000]], Count[IntegerDigits[#, 3], 1] == Count[IntegerDigits[#, 2], 1] == 3 &]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Jan 12 2017
STATUS
approved