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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A117898 Number triangle 2^abs(L(C(n,2)/3) - L(C(k,2)/3))*[k<=n] where L(j/p) is the Legendre symbol of j and p.

Table of values

n a(n)
0 1
1 1
2 1
3 2
4 2
5 1
6 1
7 1
8 2
9 1
10 1
11 1
12 2
13 1
14 1
15 2
16 2
17 1
18 2
19 2
20 1
21 1
22 1
23 2
24 1
25 1
26 2
27 1
28 1
29 1
30 2
31 1
32 1
33 2
34 1
35 1
36 2
37 2
38 1
39 2
40 2
41 1
42 2
43 2
44 1
45 1
46 1
47 2
48 1
49 1
50 2
51 1
52 1
53 2
54 1
55 1
56 1
57 2
58 1
59 1
60 2
61 1
62 1
63 2
64 1
65 1
66 2
67 2
68 1
69 2
70 2
71 1
72 2
73 2
74 1
75 2
76 2
77 1
78 1
79 1
80 2
81 1
82 1
83 2
84 1
85 1
86 2
87 1
88 1
89 2
90 1

List of values

[1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1]

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