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 | -3 |
| 3 | 14 |
| 4 | -76 |
| 5 | 441 |
| 6 | -2678 |
| 7 | 16813 |
| 8 | -108093 |
| 9 | 707451 |
| 10 | -4696017 |
| 11 | 31530792 |
| 12 | -213715953 |
| 13 | 1460072247 |
| 14 | -10042361784 |
| 15 | 69473047716 |
| 16 | -483046768116 |
| 17 | 3373552141194 |
| 18 | -23653214175084 |
| 19 | 166422650191122 |
| 20 | -1174621198245837 |
| 21 | 8314055808436788 |
| 22 | -58998774106863513 |