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 | -3 |
| 3 | -1 |
| 4 | 69 |
| 5 | 455 |
| 6 | -1155 |
| 7 | -50065 |
| 8 | -334155 |
| 9 | 4107095 |
| 10 | 112058925 |
| 11 | 491352575 |
| 12 | -24429589275 |
| 13 | -535893782425 |
| 14 | 606194735325 |
| 15 | 249291355871375 |
| 16 | 4380933801391125 |
| 17 | -56204145098271625 |
| 18 | -4031655689182933875 |