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 | -6 |
| 3 | 42 |
| 4 | -350 |
| 5 | 3234 |
| 6 | -31878 |
| 7 | 328426 |
| 8 | -3494142 |
| 9 | 38093442 |
| 10 | -423344966 |
| 11 | 4778162922 |
| 12 | -54621614814 |
| 13 | 631114404258 |
| 14 | -7358619459654 |
| 15 | 86472788963370 |
| 16 | -1023093071862526 |
| 17 | 12177054520248834 |
| 18 | -145700860758056838 |
| 19 | 1751559565664348842 |
| 20 | -21145576694586256734 |