常见序列

f = {1, 1, 1, 3, 16, 125, 1296, 16807, 262144, 4782969, 100000000}
f[i] = i ^ (i - 2)//前几项特判

f = {1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845, 35357670}
//卡特兰数列

f = {0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55}//斐波那契数列

B = {1, 1, 2, 5, 15, 52, 203}//贝尔数