记a[n]=x,a[n+1]=y
由数列性质有：
a[n+2]=a[n+1]+a[n]=x+y
a[n+3]=a[n+2]+a[n+1]=x+2y
a[n+4]=a[n+3]+a[n+2]=2x+3y
a[n+5]=a[n+4]+a[n+3]=3x+5y
a[n+6]=a[n+5]+a[n+4]=5x+8y
a[n+7]=a[n+6]+a[n+5]=8x+13y
a[n+8]=a[n+7]+a[n+6]=13x+21y
a[n+9]=a[n+8]+a[n+7]=21x+34y
相加得：
a[n]+……a[n+9]=55x+88y=11*a[n+6] [第7个]
得证.