OFFSET
1,2
EXAMPLE
a(2)=6, since there are 6 9's in primes less than 100. Namely: 19, 29, 59, 79, 89, 97.
MATHEMATICA
Table[Count[IntegerDigits[Prime[Range[PrimePi[10^n - 1]]]], 9, 2], {n, 7}] (* Robert Price, Jun 16 2019 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Robert Price, Nov 11 2013
EXTENSIONS
a(14) from Giovanni Resta, Jul 20 2015
STATUS
approved