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 | 2 |
| 3 | 3 |
| 4 | -8 |
| 5 | -65 |
| 6 | 366 |
| 7 | 4284 |
| 8 | -71392 |
| 9 | -377919 |
| 10 | 28218760 |
| 11 | -249587877 |
| 12 | -14356069056 |
| 13 | 587285561746 |
| 14 | 153563287892 |
| 15 | -954498079774950 |
| 16 | 39921820513516256 |
| 17 | 533333406684245239 |
| 18 | -158979463609003391970 |
| 19 | 8008135971419079188618 |
| 20 | 190727236066813163686860 |