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 | -23 |
| 5 | -119 |
| 6 | -359 |
| 7 | 1681 |
| 8 | 38641 |
| 9 | 269137 |
| 10 | 599761 |
| 11 | -22461119 |
| 12 | -347288039 |
| 13 | -8704873319 |
| 14 | -73184815703 |
| 15 | 16491842641 |
| 16 | 26323288948321 |
| 17 | 725566429691041 |
| 18 | 7867441656997921 |
| 19 | -20568394299884543 |
| 20 | -4768992217846599479 |
| 21 | -108339469662214468439 |