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) |
|---|---|
| 1 | 0 |
| 2 | 12 |
| 3 | 207 |
| 4 | 1392 |
| 5 | 7455 |
| 6 | 36540 |
| 7 | 171591 |
| 8 | 785856 |
| 9 | 3538215 |
| 10 | 15727740 |
| 11 | 69204927 |
| 12 | 301988592 |
| 13 | 1308621327 |
| 14 | 5637142812 |
| 15 | 24159189015 |
| 16 | 103079212800 |
| 17 | 438086661591 |
| 18 | 1855425868956 |
| 19 | 7834020344655 |
| 20 | 32985348829680 |
| 21 | 138538465095807 |
| 22 | 580542139461372 |
| 23 | 2427721674124647 |