

A039506


Number of cluster primes less than 10^n.


6



3, 23, 99, 420, 1807, 8287, 40017, 202208, 1059807, 5736717, 31911465, 182019293, 1060723057
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OFFSET

1,1


COMMENTS

The Blecksmith paper gives incorrect values of a(n) for n>8.  T. D. Noe, Jul 21 2006


LINKS

Table of n, a(n) for n=1..13.
Richard Blecksmith, Paul ErdÅ‘s and J. L. Selfridge, Cluster Primes, Amer. Math. Monthly, 106 (1999), 4348.
Eric Weisstein's World of Mathematics, Cluster Prime.
Index entries for sequences related to numbers of primes in various ranges


CROSSREFS

Cf. A038133, A038134, A039507.
Cf. A121044, A121045 (cluster primes near 10^n).
Sequence in context: A301580 A112459 A197303 * A196970 A197557 A225671
Adjacent sequences: A039503 A039504 A039505 * A039507 A039508 A039509


KEYWORD

nonn,more


AUTHOR

Christian G. Bower, Feb 15 1999


EXTENSIONS

Corrected by T. D. Noe, Jul 21 2006


STATUS

approved



