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 | -1 |
| 2 | 9 |
| 3 | -188 |
| 4 | 7210 |
| 5 | -442534 |
| 6 | 39778322 |
| 7 | -4926514200 |
| 8 | 804271290024 |
| 9 | -167367096770256 |
| 10 | 43244394345493968 |
| 11 | -13583108127289832592 |
| 12 | 5097183064576208028096 |
| 13 | -2252211248747050526401296 |
| 14 | 1157380447302779717382178416 |
| 15 | -684423139836843936246492092928 |