A(x;t)=1+(1+t)*x+(2+4*t+t^2)*x^2+(5+15*t+9*t^2+t^3)*x*3+。..
三角形开始:
n\k[0][1][2][3][4][5][6][7][8][9]
[0] 1;
[1] 1, 1;
[2] 2, 4, 1;
[3] 5, 15, 9, 1;
[4] 14, 56, 56, 16, 1;
[5] 42, 210, 300, 150, 25, 1;
[6] 132, 792, 1485, 1100, 330, 36, 1;
[7] 429, 3003, 7007, 7007, 3185, 637, 49, 1;
[8] 1430, 11440, 32032, 40768, 25480, 7840, 1120, 64, 1;
[9] 4862, 43758, 143208, 222768, 179928, 77112, 17136, 1836, 81, 1;
[10] ...