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 | -5 |
| 4 | -15 |
| 5 | 0 |
| 6 | 170 |
| 7 | 619 |
| 8 | 69 |
| 9 | -8351 |
| 10 | -33601 |
| 11 | -8446 |
| 12 | 480679 |
| 13 | 2078534 |
| 14 | 830739 |
| 15 | -30221481 |
| 16 | -138791261 |
| 17 | -76306831 |
| 18 | 2009474129 |
| 19 | 9742939809 |
| 20 | 6811893809 |
| 21 | -138835809721 |
| 22 | -708398431831 |
| 23 | -599833654686 |
| 24 | 9861055840019 |
| 25 | 52859680413599 |
| 26 | 52446605719469 |