N

$4\pi \times E_{\text{min}}\left(N\right)$

2

0

3, 4

−1

5

−2

6

−2.29289

7

−3.58579

8

−3.45603

9

−4.32627

10

−4.86986

11

−5.80649

12

−5.86948

13

−6.94895

14

−7.14629

15

−8.10289

16

−8.37101

17

−9.17890

18

−9.63666

19

−10.6340

20

−10.9049

21

−11.7208