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 | 4 |
| 5 | 15 |
| 6 | 104 |
| 7 | 644 |
| 8 | 3696 |
| 9 | 23388 |
| 10 | 151842 |
| 11 | 979110 |
| 12 | 6445659 |
| 13 | 43148963 |
| 14 | 290832906 |
| 15 | 1977914328 |
| 16 | 13574296048 |
| 17 | 93787977144 |
| 18 | 651970844448 |
| 19 | 4558718881927 |
| 20 | 32038664402074 |
| 21 | 226200869873851 |
| 22 | 1603811085640698 |
| 23 | 11415385190127413 |
| 24 | 81538284501095235 |