OFFSET
1,1
COMMENTS
For n >= 3, I can show 8 <= a(n) <= 13 and I highly suspect that 10 <= a(n) <= 13 from empirical evidence.
If n >= 3, there are 15 integers 0 <= x < 10^n with x == 0,1 or -1 mod 5^n and
x == 0, 1, -1, 2^(n-1)-1 or 2^(n-1)+1 mod 2^n, and a(n) is the number of these
that are >= 10^(n-1). - Robert Israel, Jul 07 2014
LINKS
Eric M. Schmidt, Table of n, a(n) for n = 1..1000
MAPLE
f:= n ->
nops(select(`>=`, {seq(seq(chrem([a, b], [2^n, 5^n]), a={0, 1, 2^(n-1)-1, 2^(n-1)+1, -1}), b={0, 1, -1})}, 10^(n-1))):
seq(f(n), n=1..100); # Robert Israel, Jul 07 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
David W. Wilson, Sep 28 2002
STATUS
approved