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 | 0 |
| 4 | 0 |
| 5 | -1 |
| 6 | -15 |
| 7 | -140 |
| 8 | -1050 |
| 9 | -6951 |
| 10 | -42273 |
| 11 | -232870 |
| 12 | -949740 |
| 13 | 2401399 |
| 14 | 149618469 |
| 15 | 2979464124 |
| 16 | 47639256210 |
| 17 | 683529622229 |
| 18 | 9045426379611 |
| 19 | 109599657976942 |
| 20 | 1148191101672384 |
| 21 | 8033814119097459 |
| 22 | -50834295574038207 |
| 23 | -3977581842278623216 |
| 24 | -119536187842156328034 |