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 | 0 |
| 1 | -1 |
| 2 | 0 |
| 3 | -4 |
| 4 | 5 |
| 5 | -20 |
| 6 | 44 |
| 7 | -125 |
| 8 | 316 |
| 9 | -840 |
| 10 | 2185 |
| 11 | -5736 |
| 12 | 15000 |
| 13 | -39289 |
| 14 | 102840 |
| 15 | -269260 |
| 16 | 704909 |
| 17 | -1845500 |
| 18 | 4831556 |
| 19 | -12649205 |
| 20 | 33116020 |
| 21 | -86698896 |
| 22 | 226980625 |
| 23 | -594243024 |
| 24 | 1555748400 |
| 25 | -4073002225 |
| 26 | 10663258224 |
| 27 | -27916772500 |
| 28 | 73087059221 |
| 29 | -191344405220 |
| 30 | 500946156380 |
| 31 | -1311494063981 |
| 32 | 3433536035500 |
| 33 | -8989114042584 |
| 34 | 23533806092185 |
| 35 | -61612304234040 |