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 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 2 |
| 8 | 56 |
| 9 | 984 |
| 10 | 14004 |
| 11 | 177140 |
| 12 | 2083560 |
| 13 | 23374060 |
| 14 | 254007320 |
| 15 | 2700941710 |
| 16 | 28293706782 |
| 17 | 293369952474 |
| 18 | 3020937207142 |
| 19 | 30967869359950 |
| 20 | 316581042622444 |
| 21 | 3231631411510936 |
| 22 | 32971319565628464 |
| 23 | 336462340456201700 |