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 | 2 |
| 3 | 5 |
| 4 | 8 |
| 5 | -79 |
| 6 | -1584 |
| 7 | -20539 |
| 8 | -223616 |
| 9 | -1855295 |
| 10 | -1736960 |
| 11 | 435730789 |
| 12 | 14511117312 |
| 13 | 338965239601 |
| 14 | 6202042886144 |
| 15 | 71638247035109 |
| 16 | -714560796196864 |
| 17 | -84697775518956799 |
| 18 | -3650903032332091392 |
| 19 | -115829159202293866939 |
| 20 | -2739961030150105333760 |
| 21 | -29414406825401517785039 |