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A185715 a(n) = number of primes <= n that end in 9. 5
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,29
COMMENTS
Partial sums of A185709.
LINKS
A. Granville and G. Martin, Prime number races, arXiv:math/0408319 [math.NT], 2004.
A. Granville and G. Martin, Prime number races, Amer. Math. Monthly, 113 (No. 1, 2006), 1-33.
MATHEMATICA
Accumulate[Table[If[PrimeQ[n] && Mod[n, 10] == 9, 1, 0], {n, 50}]] (* G. C. Greubel, Jul 10 2017 *)
PROG
(PARI) a(n) = sum(k=1, n, if ((k % 10)==9, isprime(k))); \\ Michel Marcus, Jul 11 2017
CROSSREFS
Sequence in context: A071839 A235044 A163857 * A111893 A121902 A087103
KEYWORD
base,nonn
AUTHOR
N. J. A. Sloane, Feb 10 2011
STATUS
approved

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Last modified September 11 15:58 EDT 2024. Contains 375836 sequences. (Running on oeis4.)