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 | 1 |
| 3 | -1 |
| 4 | -10 |
| 5 | -33 |
| 6 | -55 |
| 7 | 65 |
| 8 | 842 |
| 9 | 3230 |
| 10 | 6137 |
| 11 | -6631 |
| 12 | -102166 |
| 13 | -421705 |
| 14 | -864225 |
| 15 | 795615 |
| 16 | 14526042 |
| 17 | 63072042 |
| 18 | 136736102 |
| 19 | -102140350 |
| 20 | -2256842380 |
| 21 | -10210904245 |
| 22 | -23195817445 |
| 23 | 13298317815 |
| 24 | 371005984450 |
| 25 | 1740942920122 |
| 26 | 4120912606657 |
| 27 | -1666840127743 |