%I A008561
%S A008561 3,11,100,1001,11100,1110101,10000100111,1110011110101001,
%T A008561 1001111011001100001111110,100010101100001010000100000101000100101,
%U A008561 1001100000001111111111000111111011010101000111001110101000111
%N A008561 a(1) = 3; a(2) = 11; to get a(n), n >= 3, convert a(n-1) from base 3 
               to base 2.
%e A008561 11 in base 3 is 4 in base 10 which is 100 in base 2.
%e A008561 100 in base 3 is 9 in base 10 which is 1001 in base 2.
%Y A008561 Very similar to A008560.
%Y A008561 Sequence in context: A120587 A086914 A123996 this_sequence A072640 A154299 
               A007616
%Y A008561 Adjacent sequences: A008558 A008559 A008560 this_sequence A008562 A008563 
               A008564
%K A008561 nonn,base
%O A008561 1,1
%A A008561 N. J. A. Sloane (njas(AT)research.att.com).