%I
%S 0,0,0,0,1,0,1,0,1,1,0,0,1,0,0,1,1,0,2,0,3,0,2,0,1,1,0,0,0,0,1,0,0,0,
%T 0,1,1,0,3,2,0,0,3,0,0,2,3,0,1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,1,1,0,4,0,
%U 2,0,0,0,3,0,0,0,2,0,4,0,1,1,0,0,3,0,0,6,0,0,7,0,0,6,0,0,3,0,0,1
%N Triangle read by rows: row n gives coefficients of (1+x+x^2)^n mod n.
%e Triangle begins:
%e [0]
%e [0, 0, 0]
%e [1, 0, 1, 0, 1]
%e [1, 0, 0, 1, 0, 0, 1]
%e [1, 0, 2, 0, 3, 0, 2, 0, 1]
%e [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]
%e [1, 0, 3, 2, 0, 0, 3, 0, 0, 2, 3, 0, 1]
%p f := n > seriestolist( series( expand( (1+x+x^2)^n ) mod n, x, 2*n+1));
%Y Cf. A053200.
%K nonn,tabf
%O 0,19
%A _N. J. A. Sloane_, Feb 20 2004
