A126570 - OEIS

%I #10 Aug 10 2019 00:40:53

%S 1,1,2,1,4,3,1,6,10,5,1,8,21,20,4,1,10,36,56,35,7,1,12,55,120,126,56,6

%N Triangle read by rows: row n gives coefficients (ignoring the alternating signs) of the characteristic polynomial of the n X n circulant matrix with first two rows [2,1,0,...,0,1], [1,2,1,0,...,0].

%D William G. Harter, Physics Department, University of Arkansas; personal communication.

%e First few rows of the triangle are:

%e 1;

%e 1, 2;

%e 1, 4, 3;

%e 1, 6, 10, 5;

%e 1, 8, 21, 20, 4;

%e 1, 10, 36, 56, 35, 7;

%e 1, 12, 55, 120, 126, 56, 6;

%e ...

%e Example: Charpoly of the 4 X 4 matrix [2,1,0,1; 1,2,1,0; 0,1,2,1; 0,0,1,2] = x^4 - 8*x^3 + 21*x^2 - 20*x + 4; with a root sqrt(3)+2.

%K nonn,more,tabl

%O 1,3

%A _Gary W. Adamson_, Dec 28 2006

%E Edited by _N. J. A. Sloane_, Aug 10 2019