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 | 13 |
| 4 | 22 |
| 5 | -121 |
| 6 | -602 |
| 7 | 18581 |
| 8 | 30742 |
| 9 | -305071 |
| 10 | -2523002 |
| 11 | 61203943 |
| 12 | 303692662 |
| 13 | -4353296221 |
| 14 | -50402079002 |
| 15 | 6669149100757 |
| 16 | 11030684333782 |
| 17 | -206772189255571 |
| 18 | -3077986048956602 |
| 19 | 128970681211645873 |
| 20 | 1066578948824962102 |
| 21 | -24697503335329725121 |
| 22 | -449342758735568563802 |