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) |
|---|---|
| 1 | 1 |
| 2 | -7 |
| 3 | 42 |
| 4 | -231 |
| 5 | 1155 |
| 6 | -4998 |
| 7 | 15827 |
| 8 | -791 |
| 9 | -566244 |
| 10 | 6506955 |
| 11 | -53524611 |
| 12 | 369879930 |
| 13 | -2218053747 |
| 14 | 11306008875 |
| 15 | -43772711220 |
| 16 | 55203364377 |
| 17 | 1172838094533 |
| 18 | -16542312772356 |
| 19 | 150992704165079 |
| 20 | -1130142960861845 |
| 21 | 7290759457923816 |