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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 15 |
| 6 | 50 |
| 7 | 160 |
| 8 | 502 |
| 9 | 1545 |
| 10 | 4730 |
| 11 | 14356 |
| 12 | 43474 |
| 13 | 131145 |
| 14 | 395150 |
| 15 | 1188580 |
| 16 | 3572902 |
| 17 | 10732065 |
| 18 | 32225810 |
| 19 | 96733636 |
| 20 | 290322394 |
| 21 | 871200825 |
| 22 | 2614097750 |
| 23 | 7843255300 |
| 24 | 23531775502 |
| 25 | 70599259185 |
| 26 | 211805902490 |