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 | -1022 |
| 3 | -59043 |
| 4 | -1048552 |
| 5 | -9765505 |
| 6 | -60465456 |
| 7 | -282470209 |
| 8 | -1073701504 |
| 9 | -3486421521 |
| 10 | -9996371200 |
| 11 | -25897507801 |
| 12 | -61438362624 |
| 13 | -131631471049 |
| 14 | -202076363776 |
| 15 | 731023977375 |
| 16 | 19823278260224 |
| 17 | 353671434195551 |
| 18 | 6398803238501376 |
| 19 | 121638969342574199 |
| 20 | 2432891768176640000 |