謝謝各位。13是對的。鏈接https://oeis.org/A084829/a084829.txt

# Densest Packings of n Equal Spheres in a Sphere of Radius 1.
# Largest Possible Radii
# The results by Th. Gensane are published in the article
# Dense Packings of Equal Spheres in a Larger Sphere,
# Les Cahiers du LMPA J. Liouville 188, 2003
# Th. Gensane's data for n>40 are from private communication Nov 2005.
# Dave Boll only gave the radii without providing sphere locations.
# A comprehensive update is now performed based on the results
# provided in a private communication by Liang Yu; see WenQi Huang, Liang Yu:
# Serial Symmetrical Relocation Algorithm for the Equal Sphere Packing Problem
# http://arxiv.org/abs/1202.4149
# All results provided by Liang Yu, which were accurate only to ~= 10^-8,
# have been improved in precision by application of a multi-scale
# shaking process. The expected precision is now better than 10^-12.
# Author: Hugo Pfoertner http://www.pfoertner.org/
# URL of this file: http://www.randomwalk.de/sphere/insphr/spisbest.txt
# Date of last update: YYYY MM DD
2013 08 25
#n    Radius   Originator
 1  1.000000000000000 'common sense'
 2  0.500000000000000 'common sense'
 3  0.464101615137755 'Tammes sol.'
 4  0.449489742783178 'Tammes sol.'
 5  0.414213562373095 'Tammes sol.'
 6  0.414213562373095 'Tammes sol.'
 7  0.385913557399473 'Tammes sol.'
 8  0.378024844800586 'Tammes sol.'
 9  0.366025403784434 'Tammes sol.'
10  0.353049430235565 'Tammes sol.'
11  0.344576516755255 'Tammes sol.'
12  0.344576516755255 'Tammes sol.'
13  0.333333333333333 'Tammes sol.+0'
14  0.323504674182003 'Tammes sol.+0'
15  0.318304823107090 'Tammes sol.+0'
16  0.310975923320006 'Tammes sol.+0'
17  0.305693961648916 'Tammes sol.+0'
18  0.301296588595412 'Tammes sol.+0'
19  0.295332333638629 'Tammes sol.+0'
20  0.287890825548632 'Tammes sol.+0'
21  0.286832818044709 'Tammes sol.+0'
22  0.279342623828187 'Tammes sol.+0'
23  0.275670699448662 'Tammes sol.+0'
24  0.271341306094153 'Thierry Gensane'
25  0.271191827927395 'Tammes sol.+0'
26  0.266851270146397 'Thierry Gensane'
27  0.262232079867910 'Thierry Gensane'
28  0.260305474106206 'Thierry Gensane'
29  0.257925461381016 'Thierry Gensane'
30  0.255330557201847 'Thierry Gensane'
31  0.253116205096448 'Dave Boll'
32  0.250787447430689 'Thierry Gensane'
33  0.2487624         'Thierry Gensane' / best LY,HP: 0.248762333488756
34  0.247052660950443 'Thierry Gensane'
35  0.244833654976580 'Thierry Gensane'
36  0.243132162305941 'Thierry Gensane'
37  0.240686554958030 'Thierry Gensane'
38  0.240519371740801 'Liang Yu' / TG 2003: 0.24051470
39  0.236745238676494 'Thierry Gensane'
40  0.234999232359232 'Thierry Gensane'
41  0.232755979195002 'Thierry Gensane'
42  0.2321190         'Dave Boll' / questionable; best LY,HP: 0.232118614012800
43  0.229732953802005 'Thierry Gensane'
44  0.228163031287400 'Liang Yu' / TG 2005: 0.22815860
45  0.226911553062939 'Thierry Gensane'
46  0.225168195856191 'Dave Boll'
47  0.223507034454931 'Thierry Gensane'
48  0.222405937993816 'Thierry Gensane'
49  0.221278176587584 'Liang Yu'
50  0.219758275473346 'Liang Yu'
51  0.218550275685041 'Liang Yu' / HP 2006: 0.2178888
52  0.216930402454011 'Liang Yu' / HP 2006: 0.2167665
53  0.216288054714919 'Liang Yu' / HP 2006: 0.2157772
54  0.214920660994050 'Liang Yu' / HP 2006: 0.2146846
55  0.213441684044414 'Liang Yu' / HP 2006: 0.2132680
56  0.213067867576129 'Liang Yu' / HP 2006: 0.2126136
57  0.211309355482316 'Liang Yu' / HP 2006: 0.2108661
58  0.210480099018006 'Liang Yu' / HP 2006: 0.2103022
59  0.209759446545646 'Liang Yu' / HP 2006: 0.2096252
60  0.209426992286691 'Hugo Pfoertner'
61  0.209108658611283 'Liang Yu' / HP 2006: 0.2089123
62  0.206739152059719 'Liang Yu' / HP 2006: 0.2058170
63  0.205954915018959 'Liang Yu' / HP 2006: 0.2047140
64  0.204087153397427 'Liang Yu' / HP 2006: 0.2036646
65  0.203076034012903 'Liang Yu' / HP 2006: 0.2027475
66  0.202108753938119 'Liang Yu' / HP 2006: 0.2019158
67  0.201216625855546 'Liang Yu' / HP 2006: 0.2004429
68  0.200002226173858 'Liang Yu' / HP 2006: 0.1997220
69  0.199281531977205 'Liang Yu' / HP 2006: 0.1987922
70  0.198688727945893 'Liang Yu' / HP 2006: 0.1983310
71  0.197222124167297 'Liang Yu' / HP 2006: 0.1969787
72  0.196285910453337 'Liang Yu' / HP 2006: 0.1958001