三角形开始
n\k|。。。。1......2......3......4......5......6......7
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..1|....1
..2|....1......2
..3|....3......6......6
..4|....9.....30.....36.....24
..5|...39....150....270....240....120
..6|..189....918...1980...2520...1800....720
..7|.1107...6174..16254..25200..25200..15120...5040
..
递归关系示例:
T(5,3)=270=3*(T(4,2)+T(4,1)+T“4,4”)=3*(30+36+24);
T(6.1)=1*(T(5,0)+T(5,1)+T(5.2))=39+150。
有序林示例:
T(4.2)=30。15个无序森林由4个节点上的两个平面递增的一元二叉树组成,如下所示。我们可以用两种方式订购森林中的树木,从而形成30个有序森林。
......... ......... ...三。。。。。
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...1...4. ...1...4. ...|.....
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.
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.
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..\./.... ..\./.... ...三。。。。。
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.
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..\./.... ..\./.... ...三。。。。。
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......... ......... ...2...1.
.
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..2..4... ..3..4... ..4...3...
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..1..3... ..1..2... ..1...2...
......... ......... ..........