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 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | -3 |
| 6 | 19 |
| 7 | -67 |
| 8 | 40 |
| 9 | -1243 |
| 10 | -4299 |
| 11 | -25627 |
| 12 | -334324 |
| 13 | 627929 |
| 14 | -29742841 |
| 15 | 372632409 |
| 16 | -1946165680 |
| 17 | 128948361769 |
| 18 | 1488182579081 |
| 19 | 52394610324649 |
| 20 | 2333568937567764 |
| 21 | -5642424912729707 |
| 22 | 3857844273728205019 |