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 | 2 |
| 2 | -5 |
| 3 | 33 |
| 4 | -260 |
| 5 | 2263 |
| 6 | -20979 |
| 7 | 203124 |
| 8 | -2030121 |
| 9 | 20786694 |
| 10 | -216928144 |
| 11 | 2298911699 |
| 12 | -24673591005 |
| 13 | 267644087524 |
| 14 | -2929602893537 |
| 15 | 32317666058508 |
| 16 | -358931896710948 |
| 17 | 4010200327457883 |
| 18 | -45040693394259858 |
| 19 | 508253687784232108 |
| 20 | -5759468659295939684 |