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 | 0 |
| 2 | -1 |
| 3 | -2 |
| 4 | -7 |
| 5 | -42 |
| 6 | -341 |
| 7 | -3452 |
| 8 | -41835 |
| 9 | -590452 |
| 10 | -9511213 |
| 11 | -172182182 |
| 12 | -3460540075 |
| 13 | -76455710870 |
| 14 | -1841772619273 |
| 15 | -48043721545240 |
| 16 | -1349168210580087 |
| 17 | -40581475067022120 |
| 18 | -1301688751836211065 |
| 19 | -44352720153871514858 |
| 20 | -1599833618118922360175 |