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) |
|---|---|
| 1 | 1 |
| 2 | -3 |
| 3 | -31 |
| 4 | 229 |
| 5 | 3381 |
| 6 | -43531 |
| 7 | -870199 |
| 8 | 15953673 |
| 9 | 404197705 |
| 10 | -9612579511 |
| 11 | -295311670611 |
| 12 | 8630788777645 |
| 13 | 311791207040509 |
| 14 | -10809131718965763 |
| 15 | -449005897206417391 |
| 16 | 18008850183328692241 |
| 17 | 845687005960046315793 |
| 18 | -38519167813410200811247 |