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A127117
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A sequence of binary numbers. The first number is 1. Thereafter each number a(n) is defined using the previous number a(n-1) in the following way : a(n)=a(n-1).b(n-1) where the dot means the concatenation operation and b(n-1) stands for the first number that is not present in a(n-1), using the usual order (1, 10, 11, 100, 101, etc.).
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%I #3 Nov 11 2010 07:34:06
%S 1,10,1011,1011100,10111001000,101110010001010,1011100100010101101,
%T 10111001000101011011111,1011100100010101101111110000,
%U 101110010001010110111111000010011
%N A sequence of binary numbers. The first number is 1. Thereafter each number a(n) is defined using the previous number a(n-1) in the following way : a(n)=a(n-1).b(n-1) where the dot means the concatenation operation and b(n-1) stands for the first number that is not present in a(n-1), using the usual order (1, 10, 11, 100, 101, etc.).
%H Nicolas Wicker, <a href="/A127117/a127117.txt">Tcl program</a>
%e a(3)=1011 because a(2)=10 and 0, 1 and 10 are present in a(2) but 11 is not, so we append 11 to a(2) getting 10.11=1011.
%K easy,nonn,base
%O 1,2
%A Nicolas Wicker (wicker(AT)igbmc.u-strasbg.fr), Mar 21 2007
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