OFFSET
1,1
COMMENTS
Number of brilliant numbers having 2n or 2n-1 digits.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..24
PROG
(PARI) a(n)=binomial(primepi(10^n)-primepi(10^(n-1))+1, 2)
\\ Charles R Greathouse IV, May 03 2012
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Sep 02 2003
EXTENSIONS
a(14) from Ray Chandler, Jul 21 2005
STATUS
approved