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 | 0 |
| 3 | 3 |
| 4 | -14 |
| 5 | 80 |
| 6 | -479 |
| 7 | 3024 |
| 8 | -19802 |
| 9 | 129114 |
| 10 | -740172 |
| 11 | 1569150 |
| 12 | 66402733 |
| 13 | -2071117841 |
| 14 | 47637088903 |
| 15 | -1025499372275 |
| 16 | 21965630892954 |
| 17 | -479007175968646 |
| 18 | 10740252324008140 |
| 19 | -248679637522491506 |
| 20 | 5956075167341406752 |
| 21 | -147619197124939380988 |
| 22 | 3784960110596636657926 |