a(n)是条目和等于n且没有零行或列的非负整数矩阵的数目,行和弱递减。a(3)=25矩阵:
[1 1 1] [1 2] [2 1] [3]
.
[1 1] [1 1] [1 1 0] [1 0 1] [0 1 1] [2] [0 2] [2 0]
[1 0] [0 1] [0 0 1] [0 1 0] [1 0 0] [1] [1 0] [0 1]
.
[1] [1 0] [0 1] [1 0] [0 1] [1 0 0] [1 0 0] [0 1] [1 0]
[1] [1 0] [0 1] [0 1] [1 0] [0 1 0] [0 0 1] [1 0] [0 1]
[1] [0 1] [1 0] [1 0] [0 1] [0 0 1] [0 1 0] [1 0] [0 1]
.
[0 1 0] [0 1 0] [0 0 1] [0 0 1]
[1 0 0] [0 0 1] [1 0 0] [0 1 0]
[0 0 1][1 0 0][0 1 0][1 0](结束)