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 | 1 |
| 3 | 120 |
| 4 | 2016 |
| 5 | 32640 |
| 6 | 130816 |
| 7 | 523776 |
| 8 | 2096128 |
| 9 | 8386560 |
| 10 | 134209536 |
| 11 | 536854528 |
| 12 | 2147450880 |
| 13 | 34359607296 |
| 14 | 549755289600 |
| 15 | 2199022206976 |
| 16 | 8796090925056 |
| 17 | 35184367894528 |
| 18 | 140737479966720 |
| 19 | 562949936644096 |
| 20 | 2251799780130816 |