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例子
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递归:a(n)=Sum_{k=0..n-1}A022169号(n-1,k)*a(k)
如下图所示:
a(2)=1*(1)+6*(1”+1*(2)=9;
a(3)=1*(1)+31*(2)+1*(9)=103;
a(4)=1*(1)+156*(1)+806*(2)+156*(9)+1*(103)=3276。
1;
1, 1;
1, 6, 1;
1, 31, 31, 1;
1, 156, 806, 156, 1;
1, 781, 20306, 20306, 781, 1;
1, 3906, 508431, 2558556, 508431, 3906, 1; ...
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