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 | -6 |
| 2 | -37 |
| 3 | 676 |
| 4 | 2882 |
| 5 | 12502 |
| 6 | -196209 |
| 7 | -856850 |
| 8 | -3740697 |
| 9 | 58876883 |
| 10 | 257003504 |
| 11 | 1121852777 |
| 12 | -17656510365 |
| 13 | -77073076671 |
| 14 | -336434457597 |
| 15 | 5295048110651 |
| 16 | 23113603862267 |
| 17 | 100894018986142 |
| 18 | -1587942800101489 |
| 19 | -6931585922526870 |
| 20 | -30257313674299627 |
| 21 | 476211413709501353 |