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A091121
Number of primes of the form 7k+2 less than 10^n.
5
1, 4, 27, 203, 1584, 13065, 110771, 960114, 8474796, 75841428, 686342043, 6267979692, 57677527046, 534156912056
OFFSET
1,2
COMMENTS
Computed by T. D. Noe, Dec 19 2003
LINKS
Eric Weisstein's World of Mathematics, Modular Prime Counting Function
MATHEMATICA
p = Select[Table[7 i + 2, {i, 0, 10^7}], PrimeQ[#] &]; Table[Count[p, x_ /; x < 10^n], {n, 7}] (* Robert Price, May 28 2019 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Eric W. Weisstein, Dec 19 2003
EXTENSIONS
a(10) from Robert G. Wilson v, Dec 22 2003
a(11)-a(14) from Hiroaki Yamanouchi, Oct 14 2014
STATUS
approved