OFFSET
1,2
EXAMPLE
a(2)=9, since there are 9 1's in primes less than 100. Namely: 11, 13, 17, 19, 31, 41, 61, 71. Note that 11 counts for two.
MATHEMATICA
Table[Count[IntegerDigits[Prime[Range[PrimePi[10^n - 1]]]], 1, 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