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 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 26 |
| 6 | 100 |
| 7 | 365 |
| 8 | 1302 |
| 9 | 4606 |
| 10 | 16284 |
| 11 | 57762 |
| 12 | 205964 |
| 13 | 738804 |
| 14 | 2666248 |
| 15 | 9678461 |
| 16 | 35324902 |
| 17 | 129579254 |
| 18 | 477507628 |
| 19 | 1767001046 |
| 20 | 6563596132 |
| 21 | 24465218444 |
| 22 | 91480466488 |
| 23 | 343055419346 |
| 24 | 1289895758716 |
| 25 | 4861929624236 |
| 26 | 18367319517720 |
| 27 | 69533483807140 |
| 28 | 263747817532632 |