The output as an image with colors is:
Plaintext output:
[bengt@bengt-ssd 4ce622847577dbed351a]$ python term_colors.py
System colors:
RGB color cube, 6x6x6:
16 - #000000
17 - #000033
18 - #000066
19 - #000099
20 - #0000cc
21 - #0000ff
22 - #003300
23 - #003333
24 - #003366
25 - #003399
26 - #0033cc
27 - #0033ff
28 - #006600
29 - #006633
30 - #006666
31 - #006699
32 - #0066cc
33 - #0066ff
34 - #009900
35 - #009933
36 - #009966
37 - #009999
38 - #0099cc
39 - #0099ff
40 - #00cc00
41 - #00cc33
42 - #00cc66
43 - #00cc99
44 - #00cccc
45 - #00ccff
46 - #00ff00
47 - #00ff33
48 - #00ff66
49 - #00ff99
50 - #00ffcc
51 - #00ffff
52 - #330000
53 - #330033
54 - #330066
55 - #330099
56 - #3300cc
57 - #3300ff
58 - #333300
59 - #333333
60 - #333366
61 - #333399
62 - #3333cc
63 - #3333ff
64 - #336600
65 - #336633
66 - #336666
67 - #336699
68 - #3366cc
69 - #3366ff
70 - #339900
71 - #339933
72 - #339966
73 - #339999
74 - #3399cc
75 - #3399ff
76 - #33cc00
77 - #33cc33
78 - #33cc66
79 - #33cc99
80 - #33cccc
81 - #33ccff
82 - #33ff00
83 - #33ff33
84 - #33ff66
85 - #33ff99
86 - #33ffcc
87 - #33ffff
88 - #660000
89 - #660033
90 - #660066
91 - #660099
92 - #6600cc
93 - #6600ff
94 - #663300
95 - #663333
96 - #663366
97 - #663399
98 - #6633cc
99 - #6633ff
100 - #666600
101 - #666633
102 - #666666
103 - #666699
104 - #6666cc
105 - #6666ff
106 - #669900
107 - #669933
108 - #669966
109 - #669999
110 - #6699cc
111 - #6699ff
112 - #66cc00
113 - #66cc33
114 - #66cc66
115 - #66cc99
116 - #66cccc
117 - #66ccff
118 - #66ff00
119 - #66ff33
120 - #66ff66
121 - #66ff99
122 - #66ffcc
123 - #66ffff
124 - #990000
125 - #990033
126 - #990066
127 - #990099
128 - #9900cc
129 - #9900ff
130 - #993300
131 - #993333
132 - #993366
133 - #993399
134 - #9933cc
135 - #9933ff
136 - #996600
137 - #996633
138 - #996666
139 - #996699
140 - #9966cc
141 - #9966ff
142 - #999900
143 - #999933
144 - #999966
145 - #999999
146 - #9999cc
147 - #9999ff
148 - #99cc00
149 - #99cc33
150 - #99cc66
151 - #99cc99
152 - #99cccc
153 - #99ccff
154 - #99ff00
155 - #99ff33
156 - #99ff66
157 - #99ff99
158 - #99ffcc
159 - #99ffff
160 - #cc0000
161 - #cc0033
162 - #cc0066
163 - #cc0099
164 - #cc00cc
165 - #cc00ff
166 - #cc3300
167 - #cc3333
168 - #cc3366
169 - #cc3399
170 - #cc33cc
171 - #cc33ff
172 - #cc6600
173 - #cc6633
174 - #cc6666
175 - #cc6699
176 - #cc66cc
177 - #cc66ff
178 - #cc9900
179 - #cc9933
180 - #cc9966
181 - #cc9999
182 - #cc99cc
183 - #cc99ff
184 - #cccc00
185 - #cccc33
186 - #cccc66
187 - #cccc99
188 - #cccccc
189 - #ccccff
190 - #ccff00
191 - #ccff33
192 - #ccff66
193 - #ccff99
194 - #ccffcc
195 - #ccffff
196 - #ff0000
197 - #ff0033
198 - #ff0066
199 - #ff0099
200 - #ff00cc
201 - #ff00ff
202 - #ff3300
203 - #ff3333
204 - #ff3366
205 - #ff3399
206 - #ff33cc
207 - #ff33ff
208 - #ff6600
209 - #ff6633
210 - #ff6666
211 - #ff6699
212 - #ff66cc
213 - #ff66ff
214 - #ff9900
215 - #ff9933
216 - #ff9966
217 - #ff9999
218 - #ff99cc
219 - #ff99ff
220 - #ffcc00
221 - #ffcc33
222 - #ffcc66
223 - #ffcc99
224 - #ffcccc
225 - #ffccff
226 - #ffff00
227 - #ffff33
228 - #ffff66
229 - #ffff99
230 - #ffffcc
231 - #ffffff
Grayscale ramp, with RGB grays:
232 - #000000
233 - #101010
234 - #202020
235 - #303030
236 - #404040
237 - #505050
238 - #606060
239 - #707070
240 - #808080
241 - #909090
242 - #a0a0a0
243 - #b0b0b0
244 - #c0c0c0
245 - #d0d0d0
246 - #e0e0e0
247 - #f0f0f0
248 - #101010
249 - #111111
250 - #121212
251 - #131313
252 - #141414
253 - #151515
254 - #161616
255 - #171717
[bengt@bengt-ssd 4ce622847577dbed351a]$