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 | -1 |
| 5 | 4 |
| 6 | 3 |
| 7 | 4 |
| 8 | 15 |
| 9 | -14 |
| 10 | 65 |
| 11 | 224 |
| 12 | -143 |
| 13 | 1824 |
| 14 | 1441 |
| 15 | 12882 |
| 16 | 50959 |
| 17 | -151420 |
| 18 | 898979 |
| 19 | 5337220 |
| 20 | 20799 |
| 21 | 188372002 |
| 22 | -733599 |
| 23 | 6648401344 |
| 24 | 39471457217 |
| 25 | -234341035456 |
| 26 | 2785299158305 |
| 27 | 24790831385826 |
| 28 | 98497628929855 |
| 29 | 4377139749257604 |
| 30 | -12158771603059997 |