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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | -6 |
| 4 | -90 |
| 5 | 45 |
| 6 | 5607 |
| 7 | 8316 |
| 8 | -616572 |
| 9 | -2517075 |
| 10 | 106354215 |
| 11 | 779869134 |
| 12 | -26562900078 |
| 13 | -299503403199 |
| 14 | 9075456298755 |
| 15 | 144911485323000 |
| 16 | -4066415773786872 |
| 17 | -87372799002303111 |
| 18 | 2313066895842715947 |
| 19 | 64609858869087786210 |
| 20 | -1627745411473223627970 |