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 | -7 |
| 5 | -7 |
| 6 | 73 |
| 7 | 335 |
| 8 | -687 |
| 9 | -12367 |
| 10 | -19471 |
| 11 | 461119 |
| 12 | 2839561 |
| 13 | -15282199 |
| 14 | -260138759 |
| 15 | -15084017 |
| 16 | 22560194593 |
| 17 | 113205762401 |
| 18 | -1856685484703 |
| 19 | -23353924295169 |
| 20 | 115492830956953 |
| 21 | 3999727786726617 |
| 22 | 5211807618131753 |
| 23 | -646193037236457649 |