OFFSET
1,7
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
a(7)=2 as 7th prime 17 is 122 in base-3 representation.
MATHEMATICA
a2[n_] := Length[Cases[IntegerDigits[Prime[n], 3], 2]]
DigitCount[Prime[Range[90]], 3, 2] (* Harvey P. Dale, May 11 2016 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Zak Seidov Aug 11 2002
STATUS
approved