cp's OEIS Frontend

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.

A246904 Irregular triangular array: every periodic simple continued fraction CF represents a quadratic irrational (c + f*sqrt(d))/b, where b,c,f,d are integers and d is squarefree. Row n of this array shows the distinct values of d as CF ranges through the periodic continued fractions having period an n-tuple of 1s and 2s.

Table of values

n a(n)
1 2
2 5
3 2
4 3
5 5
6 2
7 5
8 10
9 85
10 2
11 3
12 5
13 6
14 30
15 221
16 2
17 5
18 13
19 65
20 145
21 290
22 533
23 2813
24 2
25 3
26 5
27 10
28 42
29 85
30 87
31 105
32 210
33 455
34 1365
35 1517
36 7565
37 2
38 5
39 29
40 58
41 74
42 149
43 185
44 442
45 565
46 901
47 2026
48 2117
49 2210
50 3973
51 10001
52 11026
53 16133
54 18229
55 2
56 3
57 5
58 6
59 26
60 30

List of values

[2, 5, 2, 3, 5, 2, 5, 10, 85, 2, 3, 5, 6, 30, 221, 2, 5, 13, 65, 145, 290, 533, 2813, 2, 3, 5, 10, 42, 85, 87, 105, 210, 455, 1365, 1517, 7565, 2, 5, 29, 58, 74, 149, 185, 442, 565, 901, 2026, 2117, 2210, 3973, 10001, 11026, 16133, 18229, 2, 3, 5, 6, 26, 30]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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