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 | 11 |
| 3 | 0 |
| 4 | 20 |
| 5 | 88 |
| 6 | 242 |
| 7 | 627 |
| 8 | 2604 |
| 9 | 8137 |
| 10 | 28727 |
| 11 | 101137 |
| 12 | 350450 |
| 13 | 1221711 |
| 14 | 4290711 |
| 15 | 14968081 |
| 16 | 52427734 |
| 17 | 183691236 |
| 18 | 643194452 |
| 19 | 2252416158 |
| 20 | 7891461835 |
| 21 | 27639419217 |
| 22 | 96818359023 |
| 23 | 339160988868 |
| 24 | 1188063187221 |
| 25 | 4161765906348 |
| 26 | 14578893452507 |