%I #20 Jan 12 2016 03:11:31

%S 3,23,99,420,1807,8287,40017,202208,1059807,5736717,31911465,

%T 182019293,1060723057

%N Number of cluster primes less than 10^n.

%C The Blecksmith paper gives incorrect values of a(n) for n>8. - _T. D. Noe_, Jul 21 2006

%H Richard Blecksmith, Paul Erdős and J. L. Selfridge, <a href="http://www.jstor.org/stable/2589585">Cluster Primes</a>, Amer. Math. Monthly, 106 (1999), 43-48.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ClusterPrime.html">Cluster Prime.</a>

%H <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a>

%Y Cf. A038133, A038134, A039507.

%Y Cf. A121044, A121045 (cluster primes near 10^n).

%K nonn,more

%O 1,1

%A _Christian G. Bower_, Feb 15 1999

%E Corrected by _T. D. Noe_, Jul 21 2006