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 | 2 |
| 4 | -8 |
| 5 | -104 |
| 6 | -688 |
| 7 | -3088 |
| 8 | -128 |
| 9 | 209536 |
| 10 | 3145472 |
| 11 | 29795072 |
| 12 | 139389952 |
| 13 | -1715047424 |
| 14 | -60056147968 |
| 15 | -1004215072768 |
| 16 | -10305404960768 |
| 17 | -1945682345984 |
| 18 | 2949643589844992 |
| 19 | 84438462955323392 |
| 20 | 1458284922371571712 |
| 21 | 12032890515685113856 |
| 22 | -245515800089314459648 |