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 | -2 |
| 4 | -1 |
| 5 | 8 |
| 6 | 10 |
| 7 | -37 |
| 8 | -84 |
| 9 | 168 |
| 10 | 660 |
| 11 | -624 |
| 12 | -4950 |
| 13 | 583 |
| 14 | 35464 |
| 15 | 23166 |
| 16 | -240513 |
| 17 | -359008 |
| 18 | 1511640 |
| 19 | 3898100 |
| 20 | -8387664 |
| 21 | -36522256 |
| 22 | 35444728 |
| 23 | 311764768 |
| 24 | -25659766 |
| 25 | -2466384737 |
| 26 | -1793133360 |
| 27 | 18077558170 |
| 28 | 28951038285 |
| 29 | -120750295320 |
| 30 | -330486900870 |