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 | 0 |
| 6 | 1 |
| 7 | 7 |
| 8 | 28 |
| 9 | 84 |
| 10 | 210 |
| 11 | 462 |
| 12 | 1386 |
| 13 | 13728 |
| 14 | 171171 |
| 15 | 1686685 |
| 16 | 13461448 |
| 17 | 91495768 |
| 18 | 551777772 |
| 19 | 3142726692 |
| 20 | 19787406360 |
| 21 | 172188951144 |
| 22 | 1999835600301 |
| 23 | 24655331721867 |
| 24 | 285725747201356 |
| 25 | 3034790658153100 |
| 26 | 29876851476502030 |