f[1]=f[2]=0 f[1] = f[2] = 0f[1]=f[2]=0
对于 i>=3i>=3i>=3 , f[i]=7∗f[i−1]+6∗f[i−2]+4∗3if[i] = 7*f[i-1] + 6*f[i-2] + 4*3^if[i]=7∗f[i−1]+6∗f[i−2]+4∗3i
求 f[n]f[n]f[n]
答案模 100000000710000000071000000007
想了半天实在不会了，求助大佬
