OFFSET
1,2
FORMULA
a(n) ~ 10^n. - Charles R Greathouse IV, May 21 2014
EXAMPLE
a(2)=15 because there are 15 primes not greater than 541 (the 100th prime) that contain a 5's digit. Namely: 5, 53 59, 151, 157, 251, 257, 353, 359, 457, 503, 509, 521, 523, 541.
MATHEMATICA
cnt = 0; Table[Do[p = Prime[k]; If[MemberQ[IntegerDigits[p], 5], cnt++], {k, 10^(n - 1) + 1, 10^n}]; cnt, {n, 5}] (* T. D. Noe, Nov 13 2013 *)
CROSSREFS
KEYWORD
more,nonn,base
AUTHOR
Robert Price, Nov 13 2013
STATUS
approved