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 | 6 |
| 3 | 20 |
| 4 | 81 |
| 5 | 324 |
| 6 | 1296 |
| 7 | 5184 |
| 8 | 20736 |
| 9 | 82944 |
| 10 | 331776 |
| 11 | 1327104 |
| 12 | 5308416 |
| 13 | 21233664 |
| 14 | 84934656 |
| 15 | 339738624 |
| 16 | 1358954496 |
| 17 | 5435817984 |
| 18 | 21743271936 |
| 19 | 86973087744 |
| 20 | 347892350976 |
| 21 | 1391569403904 |
| 22 | 5566277615616 |
| 23 | 22265110462464 |
| 24 | 89060441849856 |