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 | 1 |
| 3 | 3 |
| 4 | 22 |
| 5 | 225 |
| 6 | 3421 |
| 7 | 73668 |
| 8 | 2222977 |
| 9 | 93033615 |
| 10 | 5393456986 |
| 11 | 433396737873 |
| 12 | 48429436851577 |
| 13 | 7548123580987080 |
| 14 | 1646092439020192801 |
| 15 | 503469306031901522043 |
| 16 | 216430661498688457821022 |
| 17 | 130959358877474026010486145 |
| 18 | 111687660283090149155082836341 |