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 | 0 |
| 4 | 1 |
| 5 | 4 |
| 6 | 18 |
| 7 | 79 |
| 8 | 326 |
| 9 | 1278 |
| 10 | 4875 |
| 11 | 17978 |
| 12 | 64720 |
| 13 | 227842 |
| 14 | 787546 |
| 15 | 2678207 |
| 16 | 8982754 |
| 17 | 29761361 |
| 18 | 97558039 |
| 19 | 316778169 |
| 20 | 1019996738 |
| 21 | 3259673935 |
| 22 | 10347077497 |
| 23 | 32644696187 |
| 24 | 102425388286 |
| 25 | 319754805262 |