■フィボナッチ数魔方陣(その1)
フィボナッチ数だけからなる3方陣で、各行の積和と各列の積和等しくなるものがある。
a11=F(x+3),a12=F(x-4),a13=F(x+1)
a21=F(x-2),a22=F(x+0),a23=F(x+2)
a31=F(x-1),a32=F(x+4),a33=F(x-3)
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F(x-4)=F(x-2)-F(x-3)=-3F(x+1)+5F(x+0)
F(x-3)=F(x-1)-F(x-2)=2F(x+1)-3F(x+0)
F(x-2)=F(x+0)-F(x-1)=-F(x+1)+2F(x+0)
F(x-1)=F(x+1)-F(x+0)
F(x+0)=F(x+0)
F(x+1)=F(x+1)
F(x+2)=F(x+1)+F(x+0)
F(x+3)=F(x+2)+F(x+1)=2F(x+1)+F(x+0)
F(x+4)=F(x+3)+F(x+2)=3F(x+1)+2F(x+0)
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各行の積和
F(x+3)F(x-4)F(x+1)+F(x-2)F(x+0)F(x+2)+F(x-1)F(x+4)F(x-3)
={2F(x+1)+F(x+0)}{-3F(x+1)+5F(x+0)}F(x+1)
+{-F(x+1)+2F(x+0)}F(x+0){F(x+1)+F(x+0)}
+{F(x+1)-F(x+0)}{3F(x+1)+2F(x+0)}{2F(x+1)-3F(x+0)}
=(-6g^2+7fg+5f^2)g=-6g^3+7fg^2+5f^2g
+(-g^2+fg+2f^2)f=-fg^2+f^2g+2f^3
+(3g^2-fg-2f^2)(2g-3f)=6g^3-11fg^2-f^2g+6f^3
=-5fg^2+5f^2g+8f^3
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各列の積和
F(x+3)F(x-2)F(x-1)+F(x-4)F(x+0)F(x+4)+F(x+1)F(x+2)F(x-3)
={2F(x+1)+F(x+0)}[-F(x+1)+2F(x+0)]{F(x+1)-F(x+0)}
+{-3F(x+1)+5F(x+0)}F(x+0){3F(x+1)+2F(x+0)}
+F(x+1){F(x+1)+F(x+0)}{2F(x+1)-3F(x+0)}
=(-2g^2+3fg+2f^2)(g-f)=-2g^3+5fg^2-f^2g-2f^3
+f(-9g^2+9fg+10f^2)=-9fg^2+9f^2g+10f^3
+g(2g^2-fg-3f^2)=+2g^3-fg^2-3f^2g
=-5fg^2+5f^2g+8f^3
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