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 | 0 |
| 2 | 0 |
| 3 | 12 |
| 4 | 24 |
| 5 | 60 |
| 6 | 180 |
| 7 | 588 |
| 8 | 1968 |
| 9 | 6840 |
| 10 | 24240 |
| 11 | 87252 |
| 12 | 318360 |
| 13 | 1173744 |
| 14 | 4366740 |
| 15 | 16370700 |
| 16 | 61780320 |
| 17 | 234505140 |
| 18 | 894692736 |
| 19 | 3429028116 |
| 20 | 13195862760 |
| 21 | 50968206912 |
| 22 | 197517813636 |
| 23 | 767766750564 |
| 24 | 2992650987408 |
| 25 | 11694675166500 |
| 26 | 45807740881032 |