OFFSET
1,2
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, Modular Prime Counting Function
EXAMPLE
a(2) = 5 because there are 5 primes == 1 (mod 10) less than 10^2. They are 11, 31, 41, 61 and 71.
MATHEMATICA
c = 0; k = 1; Do[While[k < 10^n, If[PrimeQ[k], c++ ]; k += 10]; Print[c], {n, 1, 10}]
CROSSREFS
KEYWORD
base,nonn,more
AUTHOR
Shyam Sunder Gupta, Aug 14 2002
EXTENSIONS
Edited by Robert G. Wilson v, Oct 03 2002
a(10) from Robert G. Wilson v, Dec 22 2003
a(11)-a(13) from Giovanni Resta, Aug 07 2018
STATUS
approved