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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 G. C. Greubel, Table of n, a(n) for n = 1..5000 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 Cf. A185705, A185706, A185708, A185709, A185711, A185712, A185714, A185715. Sequence in context: A071839 A235044 A163857 * A111893 A121902 A087103 Adjacent sequences:  A185712 A185713 A185714 * A185716 A185717 A185718 KEYWORD base,nonn AUTHOR N. J. A. Sloane, Feb 10 2011 STATUS approved

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Last modified September 21 12:03 EDT 2019. Contains 327253 sequences. (Running on oeis4.)