

A038800


Number of primes between 10n and 10n+9.


9



4, 4, 2, 2, 3, 2, 2, 3, 2, 1, 4, 1, 1, 3, 1, 2, 2, 2, 1, 4, 0, 1, 3, 2, 1, 2, 2, 2, 2, 1, 1, 3, 0, 2, 2, 2, 1, 2, 2, 1, 2, 1, 1, 3, 2, 1, 3, 1, 1, 2, 2, 0, 2, 0, 2, 1, 2, 2, 1, 2, 2, 3, 0, 1, 3, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 1, 4, 1, 0, 3, 1, 1, 3, 0, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 1
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OFFSET

0,1


COMMENTS

If n runs through the primes, the subsequence 2, 2, 2, 3, 1, 3, 2, 4, 2, 1, 3, 2, 1, 3, 1, 0, 2, 3, 2,... is created.  R. J. Mathar, Jul 19 2012
Since 431, 433, and 439 are all prime, a(43)=3.  Bobby Jacobs, Sep 25 2016


LINKS

Michael De Vlieger, Table of n, a(n) for n = 0..10000
A. Frank & P. Jacqueroux, International Contest, 2001. Numerators of Item 23


MATHEMATICA

Table[Count[Range[10 n, 10 n + 9], p_ /; PrimeQ@ p], {n, 0, 105}] (* Michael De Vlieger, Sep 25 2016 *)


PROG

(PARI) a(n) = primepi(10*n+9)  primepi(10*n); \\ Michel Marcus, Sep 26 2016


CROSSREFS

Cf. A055781, A055782, A055783, A055784.
Sequence in context: A193556 A120438 A192977 * A126712 A162232 A029676
Adjacent sequences: A038797 A038798 A038799 * A038801 A038802 A038803


KEYWORD

nonn


AUTHOR

Jeff Burch


EXTENSIONS

a(43) corrected by Bobby Jacobs, Sep 25 2016
a(101) and a(104) corrected by Michael De Vlieger, Sep 25 2016


STATUS

approved



