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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 20 |
| 6 | 51 |
| 7 | 126 |
| 8 | 392 |
| 9 | 1513 |
| 10 | 5877 |
| 11 | 21054 |
| 12 | 71270 |
| 13 | 242463 |
| 14 | 863590 |
| 15 | 3193737 |
| 16 | 11889414 |
| 17 | 43783908 |
| 18 | 159998493 |
| 19 | 586908936 |
| 20 | 2175907284 |
| 21 | 8138471667 |
| 22 | 30541703733 |
| 23 | 114620380032 |
| 24 | 430344635913 |
| 25 | 1619584557885 |
| 26 | 6116422089050 |