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 | -2 |
| 2 | 1 |
| 3 | 1 |
| 4 | -10 |
| 5 | -61 |
| 6 | -382 |
| 7 | -3489 |
| 8 | -39001 |
| 9 | -484075 |
| 10 | -6619449 |
| 11 | -99610098 |
| 12 | -1638687448 |
| 13 | -29255834780 |
| 14 | -563343011377 |
| 15 | -11639759292186 |
| 16 | -256916737692132 |
| 17 | -6034068201092777 |
| 18 | -150271333127027481 |
| 19 | -3955735249215111270 |
| 20 | -109757859467421502791 |