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 | 4 |
| 2 | 26 |
| 3 | 204 |
| 4 | 1770 |
| 5 | 16352 |
| 6 | 157696 |
| 7 | 1569096 |
| 8 | 15988652 |
| 9 | 165998624 |
| 10 | 1749696208 |
| 11 | 18673883696 |
| 12 | 201394693864 |
| 13 | 2191421381632 |
| 14 | 24028822589440 |
| 15 | 265238416143584 |
| 16 | 2944999336948944 |
| 17 | 32869042668479424 |
| 18 | 368551132961138784 |
| 19 | 4149643380825661824 |
| 20 | 46897527236429235520 |