观察一组数:-3,3,-9,15,-33,63,-129,256…则第N个数为
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![观察一组数:-3,3,-9,15,-33,63,-129,256…则第N个数为](/uploads/image/z/12480506-26-6.jpg?t=%E8%A7%82%E5%AF%9F%E4%B8%80%E7%BB%84%E6%95%B0%3A-3%2C3%2C-9%2C15%2C-33%2C63%2C-129%2C256%E2%80%A6%E5%88%99%E7%AC%ACN%E4%B8%AA%E6%95%B0%E4%B8%BA)
观察一组数:-3,3,-9,15,-33,63,-129,256…则第N个数为
观察一组数:-3,3,-9,15,-33,63,-129,256…则第N个数为
观察一组数:-3,3,-9,15,-33,63,-129,256…则第N个数为
-3,3,-9,15,-33,63,-129,255
第N项的2倍-第N+1项=第N+2项
N=1,2*(-3)-3=-9
N=2,2*(3)-(-9)=15
N=3,2*(-9)-15=-33
N=4,2*(15)-(-33)=63
N=5,2*(-33)-63=-129
N=6,2*(63)-(-129)=255
通项公式:an=(-1)^n*[2^(n+1)+(-1)^n]
第N个数为:(-1)^N*[2^(N+1)+(-1)^N]