%I A131293
%S A131293 0,1,1,11,111,11111,11111111,1111111111111,111111111111111111111,
%T A131293 1111111111111111111111111111111111,
%U A131293 1111111111111111111111111111111111111111111111111111111
%N A131293 Concatenate a(n-2) and a(n-1) to get a(n); start with a(0)=0, a(1)=1, 
               delete the leading zero. Also Fib(n)-number of '1's.
%C A131293 Interpreted as base-2 numbers the result is A063896.
%F A131293 a(n)=a(n-2)*10^ceiling(log_10(a(n-1)))+a(n-1) for n>1.
%F A131293 a(n)=(10^Fib(n)-1)/9 where Fib(n)=A000045(n).
%e A131293 a(3)=11, a(4)=111, so a(5)=a(4)a(3)=11111.
%Y A131293 Cf. A000045, A061107, A063869.
%Y A131293 Sequence in context: A117293 A015468 A037842 this_sequence A108047 A144784 
               A030175
%Y A131293 Adjacent sequences: A131290 A131291 A131292 this_sequence A131294 A131295 
               A131296
%K A131293 nonn
%O A131293 0,4
%A A131293 Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), Jun 26 2007