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.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 23 |
| 5 | 86 |
| 6 | 397 |
| 7 | 1584 |
| 8 | 6820 |
| 9 | 28002 |
| 10 | 117852 |
| 11 | 488824 |
| 12 | 2043133 |
| 13 | 8502298 |
| 14 | 35463855 |
| 15 | 147729456 |
| 16 | 615817511 |
| 17 | 2566065066 |
| 18 | 10694840588 |
| 19 | 44568760860 |
| 20 | 185743671308 |
| 21 | 774073998864 |
| 22 | 3225960662493 |
| 23 | 13444082934608 |