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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 44 |
| 5 | 208 |
| 6 | 912 |
| 7 | 3840 |
| 8 | 15808 |
| 9 | 64256 |
| 10 | 259328 |
| 11 | 1042432 |
| 12 | 4180992 |
| 13 | 16748544 |
| 14 | 67047424 |
| 15 | 268304384 |
| 16 | 1073463296 |
| 17 | 4294377472 |
| 18 | 17178624000 |
| 19 | 68716855296 |
| 20 | 274872401920 |
| 21 | 1099500093440 |
| 22 | 4398022393856 |
| 23 | 17592135712768 |
| 24 | 70368639320064 |