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A073508 Number of primes == 9 (mod 10) less than 10^n. 4
0, 5, 38, 303, 2390, 19593, 166032, 1440186, 12711333, 113761326, 1029509896, 9401974132, 86516371101 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
This and the related sequences A073505-A073517 and A006880, A073548-A073565 are included because there is interest in the distribution of primes by their initial or final digits.
LINKS
Eric Weisstein's World of Mathematics, Modular Prime Counting Function
FORMULA
A073505(n) + A073506(n) + A073507(n) + a(n) + 2 = A006880(n).
EXAMPLE
a(2) = 5 because there are 5 primes == 9 (mod 10) less than 10^2. They are 19, 29, 59, 79 and 89.
MATHEMATICA
c = 0; k = 9; Do[While[k < 10^n, If[PrimeQ[k], c++ ]; k += 10]; Print[c], {n, 1, 10}]
CROSSREFS
Sequence in context: A027323 A110079 A110082 * A282964 A357163 A357224
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

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Last modified April 18 03:01 EDT 2024. Contains 371767 sequences. (Running on oeis4.)