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 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 6 |
| 7 | 21 |
| 8 | 56 |
| 9 | 126 |
| 10 | 378 |
| 11 | 3234 |
| 12 | 34056 |
| 13 | 289575 |
| 14 | 2020018 |
| 15 | 12237225 |
| 16 | 70634928 |
| 17 | 468041756 |
| 18 | 4190274648 |
| 19 | 45557515620 |
| 20 | 499503011496 |
| 21 | 5121432107757 |
| 22 | 49183015347774 |
| 23 | 462331794763069 |
| 24 | 4579813478536296 |
| 25 | 50959878972009546 |