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 | 104 |
| 3 | 1760 |
| 4 | 39520 |
| 5 | 590720 |
| 6 | 14285056 |
| 7 | 205151232 |
| 8 | 4596467200 |
| 9 | 75375073280 |
| 10 | 1504196046848 |
| 11 | 23673049726976 |
| 12 | 525315968712704 |
| 13 | 7912159583600640 |
| 14 | 158055039529779200 |
| 15 | 2726833423421800448 |
| 16 | 51889395654107463680 |
| 17 | 840470097284214292480 |
| 18 | 16765991910040314839040 |