Question 173860
There are 2^6 or 64 possible combinations of shells that sammy can buy.
Column value of 0 means doesn't buy, 1 means buys
Column names sw,mw,lw are small, medium, and large white shells. 
Column names sb,mb,lb are small, medium, and large brown shells. 
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For example,
Row 1, would be no shells at all.
Row 5, would be small brown shells only.
Row 13 would be large white shells and small brown shells.
Row 64 would be small white, medium white, large white, small brown, medium brown, and large brown shells.
Hopefully that's clear enough.
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Row, sw, mw, lw, sb, mb, lb
1, 0, 0, 0, 0, 0, 0
2, 0, 0, 0, 0, 0, 1
3, 0, 0, 0, 0, 1, 0
4, 0, 0, 0, 0, 1, 1
5, 0, 0, 0, 1, 0, 0
6, 0, 0, 0, 1, 0, 1
7, 0, 0, 0, 1, 1, 0
8, 0, 0, 0, 1, 1, 1
9, 0, 0, 1, 0, 0, 0
10, 0, 0, 1, 0, 0, 1
11, 0, 0, 1, 0, 1, 0
12, 0, 0, 1, 0, 1, 1
13, 0, 0, 1, 1, 0, 0
14, 0, 0, 1, 1, 0, 1
15, 0, 0, 1, 1, 1, 0
16, 0, 0, 1, 1, 1, 1
17, 0, 1, 0, 0, 0, 0
18, 0, 1, 0, 0, 0, 1
19, 0, 1, 0, 0, 1, 0
20, 0, 1, 0, 0, 1, 1
21, 0, 1, 0, 1, 0, 0
22, 0, 1, 0, 1, 0, 1
23, 0, 1, 0, 1, 1, 0
24, 0, 1, 0, 1, 1, 1
25, 0, 1, 1, 0, 0, 0
26, 0, 1, 1, 0, 0, 1
27, 0, 1, 1, 0, 1, 0
28, 0, 1, 1, 0, 1, 1
29, 0, 1, 1, 1, 0, 0
30, 0, 1, 1, 1, 0, 1
31, 0, 1, 1, 1, 1, 0
32, 1, 1, 1, 1, 1, 1
33, 1, 0, 0, 0, 0, 0
34, 1, 0, 0, 0, 0, 1
35, 1, 0, 0, 0, 1, 0
36, 1, 0, 0, 0, 1, 1
37, 1, 0, 0, 1, 0, 0
38, 1, 0, 0, 1, 0, 1
39, 1, 0, 0, 1, 1, 0
40, 1, 0, 0, 1, 1, 1
41, 1, 0, 1, 0, 0, 0
42, 1, 0, 1, 0, 0, 1
43, 1, 0, 1, 0, 1, 0
44, 1, 0, 1, 0, 1, 1
45, 1, 0, 1, 1, 0, 0
46, 1, 0, 1, 1, 0, 1
47, 1, 0, 1, 1, 1, 0
48, 1, 0, 1, 1, 1, 1
49, 1, 1, 0, 0, 0, 0
50, 1, 1, 0, 0, 0, 1
51, 1, 1, 0, 0, 1, 0
52, 1, 1, 0, 0, 1, 1
53, 1, 1, 0, 1, 0, 0
54, 1, 1, 0, 1, 0, 1
55, 1, 1, 0, 1, 1, 0
56, 1, 1, 0, 1, 1, 1
57, 1, 1, 1, 0, 0, 0
58, 1, 1, 1, 0, 0, 1
59, 1, 1, 1, 0, 1, 0
60, 1, 1, 1, 0, 1, 1
61, 1, 1, 1, 1, 0, 0
62, 1, 1, 1, 1, 0, 1
63, 1, 1, 1, 1, 1, 0
64, 1, 1, 1, 1, 1, 1