%I #2 Mar 30 2012 17:31:12
%S 1,0,1,0,1,0,1,0,0,1,0,0,1,1,1,1,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,1,1,1,
%T 1,1,0,1,0,0,0,0,1,1,0,0,0,1,0,0,0,1,0,1,1,1,0,1,1,1,1,0,0,1,1,1,0,1,
%U 1,0,1,1,0,1,1,0,0,1,1,0,0,1,1,0,1,0,1,1,1,1,0,1,0,1,0,1,0,1,0,0,1,1,0,1,0
%N Write the natural numbers in base 2 in a triangle with k digits in the k-th row, as shown below. Sequence gives the leading diagonal.
%C 1
%C 10
%C 111
%C 0010
%C 11101
%C 111000...
%t t = Flatten[ IntegerDigits[ Range[660], 2]]; t[[Table[n(n + 1)/2, {n, 105}]]]
%Y Cf. A104607, A104608, A104609, A104610, A104611, A104612, A104613, A091425, A104614, A104615, A104616, A104617, A104618, A104619, A104620.
%K base,nonn
%O 1,1
%A _Robert G. Wilson v_, Mar 16 2005