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 | 6 |
| 2 | -36 |
| 3 | 216 |
| 4 | -2592 |
| 5 | 23328 |
| 6 | -311040 |
| 7 | 3265920 |
| 8 | -45349632 |
| 9 | 517321728 |
| 10 | -7336562688 |
| 11 | 88159684608 |
| 12 | -1266403590144 |
| 13 | 15771513618432 |
| 14 | -228509902503936 |
| 15 | 2921050338066432 |
| 16 | -42583086769766400 |
| 17 | 555279063084564480 |
| 18 | -8132204141176946688 |
| 19 | 107718176292801085440 |