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 | 1 |
| 2 | 6 |
| 3 | 29 |
| 4 | 128 |
| 5 | 536 |
| 6 | 2168 |
| 7 | 8556 |
| 8 | 33152 |
| 9 | 126640 |
| 10 | 478304 |
| 11 | 1789840 |
| 12 | 6646272 |
| 13 | 24519680 |
| 14 | 89956224 |
| 15 | 328437184 |
| 16 | 1194102784 |
| 17 | 4325299456 |
| 18 | 15615510016 |
| 19 | 56209986816 |
| 20 | 201798074368 |
| 21 | 722731821056 |
| 22 | 2582790830080 |
| 23 | 9211619462144 |