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 | -3 |
| 4 | -11 |
| 5 | -61 |
| 6 | -469 |
| 7 | -4711 |
| 8 | -58071 |
| 9 | -842361 |
| 10 | -13995017 |
| 11 | -261468651 |
| 12 | -5420285859 |
| 13 | -123390215413 |
| 14 | -3058937910365 |
| 15 | -82014781572431 |
| 16 | -2364353822942639 |
| 17 | -72922308541928945 |
| 18 | -2395804482405465233 |
| 19 | -83528123730918481747 |
| 20 | -3079941980238262567995 |