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 | -4 |
| 3 | 14 |
| 4 | 144 |
| 5 | 286 |
| 6 | -5080 |
| 7 | -61058 |
| 8 | -186144 |
| 9 | 4016958 |
| 10 | 73395928 |
| 11 | 468915102 |
| 12 | -4728823088 |
| 13 | -167453193314 |
| 14 | -2051810224568 |
| 15 | -406640603074 |
| 16 | 533831885402048 |
| 17 | 11987797433266302 |
| 18 | 110763307665075640 |
| 19 | -1459040819952150178 |
| 20 | -80503810962755821904 |