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A185714
a(n) = number of primes <= n that end in 7.
5
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, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 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, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
OFFSET
1,17
COMMENTS
Partial sums of A185708.
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] == 7, 1, 0], {n, 50}]] (* G. C. Greubel, Jul 10 2017 *)
KEYWORD
base,nonn
AUTHOR
N. J. A. Sloane, Feb 10 2011
STATUS
approved