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 | 20 |
| 3 | 106 |
| 4 | 576 |
| 5 | 3174 |
| 6 | 17648 |
| 7 | 98746 |
| 8 | 555104 |
| 9 | 3131854 |
| 10 | 17720880 |
| 11 | 100507554 |
| 12 | 571179792 |
| 13 | 3251459670 |
| 14 | 18535914480 |
| 15 | 105803208906 |
| 16 | 604598535360 |
| 17 | 3458315246238 |
| 18 | 19799128470896 |
| 19 | 113441876080306 |
| 20 | 650450158678256 |
| 21 | 3731985710892454 |
| 22 | 21425304596140080 |