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 | 2 |
| 4 | -15 |
| 5 | 49 |
| 6 | -98 |
| 7 | 48 |
| 8 | 561 |
| 9 | -2860 |
| 10 | 8151 |
| 11 | -12948 |
| 12 | -9282 |
| 13 | 149226 |
| 14 | -594320 |
| 15 | 1428952 |
| 16 | -1448655 |
| 17 | -5538975 |
| 18 | 37450900 |
| 19 | -122995950 |
| 20 | 239589735 |
| 21 | -37528755 |
| 22 | -1886983020 |
| 23 | 8939152560 |
| 24 | -24579514050 |
| 25 | 35197176924 |
| 26 | 51580335366 |
| 27 | -541312482256 |
| 28 | 2033695030128 |
| 29 | -4624358661240 |