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 | 9 |
| 2 | 65 |
| 3 | 471 |
| 4 | 3413 |
| 5 | 24733 |
| 6 | 179233 |
| 7 | 1298853 |
| 8 | 9412437 |
| 9 | 68209395 |
| 10 | 494295113 |
| 11 | 3582023557 |
| 12 | 25957960001 |
| 13 | 188110345129 |
| 14 | 1363185009337 |
| 15 | 9878634630295 |
| 16 | 71587804656589 |
| 17 | 518777540353453 |
| 18 | 3759441118026705 |
| 19 | 27243657291488469 |
| 20 | 197427447142906157 |
| 21 | 1430703538380753875 |