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.

A005133 Number of index n subgroups of modular group PSL_2(Z).

Table of values

n a(n)
1 1
2 1
3 4
4 8
5 5
6 22
7 42
8 40
9 120
10 265
11 286
12 764
13 1729
14 2198
15 5168
16 12144
17 17034
18 37702
19 88958
20 136584
21 288270
22 682572
23 1118996
24 2306464
25 5428800
26 9409517
27 19103988
28 44701696
29 80904113
30 163344502
31 379249288
32 711598944
33 1434840718
34 3308997062
35 6391673638
36 12921383032
37 29611074174
38 58602591708
39 119001063028
40 271331133136
41 547872065136
42 1119204224666
43 2541384297716
44 5219606253184
45 10733985041978
46 24300914061436
47 50635071045768
48 104875736986272
49 236934212877684
50 499877970985660

List of values

[1, 1, 4, 8, 5, 22, 42, 40, 120, 265, 286, 764, 1729, 2198, 5168, 12144, 17034, 37702, 88958, 136584, 288270, 682572, 1118996, 2306464, 5428800, 9409517, 19103988, 44701696, 80904113, 163344502, 379249288, 711598944, 1434840718, 3308997062, 6391673638, 12921383032, 29611074174, 58602591708, 119001063028, 271331133136, 547872065136, 1119204224666, 2541384297716, 5219606253184, 10733985041978, 24300914061436, 50635071045768, 104875736986272, 236934212877684, 499877970985660]