A185714 a(n) = number of primes <= n that end in 7.

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

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] == 7, 1, 0], {n, 50}]] (* G. C. Greubel, Jul 10 2017 *)

Crossrefs

Cf. A185705, A185706, A185708, A185709, A185711, A185712, A185714, A185715.

Sequence in context: A032556 A110592 A279759 * A168353 A053230 A194334

Adjacent sequences: A185711 A185712 A185713 * A185715 A185716 A185717

Keyword

base,nonn

Author

N. J. A. Sloane, Feb 10 2011

Status

approved