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 | -288 |
| 2 | -129168 |
| 3 | -1927296 |
| 4 | 65152656 |
| 5 | 1535768640 |
| 6 | 15223408704 |
| 7 | 98001292032 |
| 8 | 474055120080 |
| 9 | 1870878793824 |
| 10 | 6312358836000 |
| 11 | 18835985199744 |
| 12 | 50831420617152 |
| 13 | 126257508465984 |
| 14 | 292348744636032 |
| 15 | 637474437331200 |
| 16 | 1319883180896592 |
| 17 | 2610964045674432 |
| 18 | 4963491913583664 |