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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | -1 |
| 5 | 8 |
| 6 | -16 |
| 7 | 159 |
| 8 | -659 |
| 9 | 6824 |
| 10 | -46680 |
| 11 | 517581 |
| 12 | -4941685 |
| 13 | 61043344 |
| 14 | -735256328 |
| 15 | 10269016939 |
| 16 | -147207286503 |
| 17 | 2322683458544 |
| 18 | -38298239486672 |
| 19 | 677630804946393 |
| 20 | -12581447014620585 |
| 21 | 247342217288517496 |
| 22 | -5096876494438056928 |
| 23 | 110338442309322274295 |