Table

\[\sum_{i=1}^{n}i^0=n\]

\[\sum_{i=1}^{n}i^1=\frac{n(n+1)}{2}=\frac{n^2}{2}+\frac{n}{2}\]

\[\sum_{i=1}^{n}i^2=\frac{n(n+1)(2n+1)}{6}=\frac{n^3}{3}+\frac{n^2}{2}+\frac{n}{6}\]

\[\sum_{i=1}^{n}i^3=\frac{n^2(n+1)^2}{4}=\frac{n^4}{4}+\frac{n^3}{2}+\frac{n^2}{4}\]

约数个数，所有反素数

n	d(n)
1	1
2	2
4	3
6	4
12	6
24	8
36	9
48	10
60	12
120	16
180	18
240	20
360	24
720	30
840	32
1260	36
1680	40
2520	48
5040	60
7560	64
10080	72
15120	80
20160	84
25200	90
27720	96
45360	100
50400	108
55440	120
83160	128
110880	144
166320	160
221760	168
277200	180
332640	192
498960	200
554400	216
665280	224
720720	240
1081080	256
1441440	288
2162160	320
2882880	336
3603600	360
4324320	384
6486480	400
7207200	432
8648640	448
10810800	480
14414400	504
17297280	512
21621600	576
32432400	600
36756720	640
43243200	672
61261200	720
73513440	768
110270160	800
122522400	864
147026880	896
183783600	960
245044800	1008
294053760	1024
367567200	1152
551350800	1200
698377680	1280
735134400	1344