a(n,m) tabl head (triangle) for A128497 Coefficient table for sum(S(k,x)*S(k+1,x)/x,k=0..n) (Chebyshev's S-polynomials) n\m 0 1 2 3 4 5 6 7 8 9 10 ... 0 1 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 2 2 -2 1 0 0 0 0 0 0 0 0 3 0 5 -4 1 0 0 0 0 0 0 0 4 3 -8 12 -6 1 0 0 0 0 0 0 5 0 14 -28 23 -8 1 0 0 0 0 0 6 4 -20 58 -68 38 -10 1 0 0 0 0 7 0 30 -108 171 -136 57 -12 1 0 0 0 8 5 -40 188 -382 405 -240 80 -14 1 0 0 9 0 55 -308 781 -1056 828 -388 107 -16 1 0 10 6 -70 483 -1488 2488 -2472 1524 -588 138 -18 1 . . . The rows n=11..15 are: n=11: [0, 91, -728, 2678, -5408, 6604, -5132, 2593, -848, 173, -20, 1] n=12: [7, -112, 1064, -4596, 11006, -16144, 15344, -9730, 4151, -1176, 212, -22, 1] n=13: [0, 140, -1512, 7578, -21200, 36690, -41700, 32211, -17184, 6330, -1580, 255, -24, 1] n=14: [8, -168, 2100, -12072, 38972, -78436, 104746, -96392, 62428, -28668, 9278, -2068, 302, -26, 1] n=15: [0, 204, -2856, 18666, -68816, 159154, -246228, 265319, -204064, 113434, -45644, 13159, -2648, 353, -28, 1] Row sums (signed) look like A008620: [1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, ...] with g.f. 1/((1-x)*(1-x^3). Row sums (unsigned) look like |A077916|. [1, 1, 5, 10, 30, 74, 199, 515, 1355, 3540, 9276, 24276, 63565, 166405, 435665, 1140574,...] with g.f. 1/((1+x)*(1-2*x-2*x^2-x^3)). The g.f.s for the column sequences (without leading zeros) are: 1/(((1-x)^2)*(1+x)^(2*m)). Therefore, this is a Riordan lower triangular matrix (1/(1-x)^2, x/(1+x)^2). ########################################## e.o.f. #####################################################