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.

A018789 Number of subsets of { 1, ..., n } containing an arithmetic progression of length 4.

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 1
5 3
6 8
7 25
8 64
9 148
10 356
11 826
12 1863
13 4205
14 9246
15 19865
16 42935
17 90872
18 190561
19 399104
20 829883
21 1710609
22 3523315
23 7224223
24 14755538
25 30092167
26 61177910
27 124028647
28 251168840
29 507216174
30 1022829206
31 2061466047
32 4149639752

List of values

[0, 0, 0, 0, 1, 3, 8, 25, 64, 148, 356, 826, 1863, 4205, 9246, 19865, 42935, 90872, 190561, 399104, 829883, 1710609, 3523315, 7224223, 14755538, 30092167, 61177910, 124028647, 251168840, 507216174, 1022829206, 2061466047, 4149639752]