%I #13 Jan 08 2024 09:02:46

%S 1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,

%T 1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,1,1,

%U 1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,1

%N 0 iff n is of the form 4^a*(8k+7), otherwise 1.

%C 0 iff n is not the sum of three squares.

%H J.-P. Allouche and J. Shallit, <a href="https://www.cs.uwaterloo.ca/~shallit/Papers/as0.ps">The ring of k-regular sequences</a>, preprint.

%H J.-P. Allouche and J. Shallit, <a href="https://doi.org/10.1016/0304-3975(92)90001-V">The ring of k-regular sequences</a>, Theoretical Computer Sci., Vol. 98 (1992), pp. 163-197.

%H <a href="/index/Ar#2-automatic">Index entries for 2-automatic sequences</a>.

%Y 1's complement to A072401. Cf. A071377.

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Jun 12 2002