■日本の畳(その14)

m\n  1  2  3  4  5  6  7  8

1    0  1  0  1  0  1  0  1

2    1  2  3  4  6  9  13  19

3    0  3  0  4  0  6  0  10

4    1  4  4  2  3  3  3  5

5    0  6  0  3  0  2  0  2

6    1  9  6  3  2  2  2  1

7    0  13  0  3  0  2  0  2

8    1  19  10  5  2  1  2  2

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[1]4×7の部屋に14枚の畳を敷く場合,その敷き方の数は?

 (1+z)(1+z^2+z^4)/(1−z^3−z^5)

=1+z+z^2+z^3+z^4+z^5

       +z^3+z^4+z^5+z^6+z^7+z^8

             +z^5+z^6+z^7+z^8+z^9+z^10

                +z^6+z^7+z^8+z^9+z^10+z^11

                      +2z^8+2z^9+2z^10+2z^11+2z^12+2z^13+・・・

=1+z+z^2+2z^3+2z^4+3z^5+3z^6+3z^7+5z^8+4^9+4z^10+3z^11+2z^12+2z^13+・・・

z^5からz^7の係数は正しく求められている.

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[2]5×6の部屋に15枚の畳を敷く場合,その敷き方の数は?

  (1+z^4+z^6)/(1−z^4−z^6)

 1/(1−z^4−z^6)=1+z^4+z^6+(z^4+z^6)^2+・・・

=1+z^4+z^6+z^8+2z^10+・・・

  (1+z^4+z^6)/(1−z^4−z^6)

=1+z^4+z^6

  +z^4   +z^8+z^10

     +z^6   +z^10+z^12

        +z^8    +z^12+z^14+・・・

=1+2z^4+2z^6+2z^8+2z^10+2z^12+・・・

z^5からz^8の係数は正しく求められている.

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