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 | 0 |
| 1 | 4 |
| 2 | 64 |
| 3 | 1156 |
| 4 | 20736 |
| 5 | 372100 |
| 6 | 6677056 |
| 7 | 119814916 |
| 8 | 2149991424 |
| 9 | 38580030724 |
| 10 | 692290561600 |
| 11 | 12422650078084 |
| 12 | 222915410843904 |
| 13 | 4000054745112196 |
| 14 | 71778070001175616 |
| 15 | 1288005205276048900 |
| 16 | 23112315624967704576 |
| 17 | 414733676044142633476 |
| 18 | 7442093853169599697984 |