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.

A209400 Number of subsets of {1,...,n} containing a subset of the form {k,k+1,k+3} for some k.

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 2
5 7
6 19
7 46
8 107
9 242
10 535
11 1162
12 2490
13 5281
14 11108
15 23206
16 48206
17 99663
18 205218
19 421115
20 861585
21 1758249
22 3580075
23 7275377
24 14759592
25 29897683
26 60481359
27 122206014
28 246665382
29 497414751
30 1002231335
31 2017877779
32 4060069150
33 8164204342

List of values

[0, 0, 0, 0, 2, 7, 19, 46, 107, 242, 535, 1162, 2490, 5281, 11108, 23206, 48206, 99663, 205218, 421115, 861585, 1758249, 3580075, 7275377, 14759592, 29897683, 60481359, 122206014, 246665382, 497414751, 1002231335, 2017877779, 4060069150, 8164204342]