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 | 1 |
| 3 | -2 |
| 4 | 5 |
| 5 | 13 |
| 6 | 24 |
| 7 | -229 |
| 8 | -365 |
| 9 | 7394 |
| 10 | -59449 |
| 11 | -572233 |
| 12 | -7773360 |
| 13 | 151071097 |
| 14 | -578687351 |
| 15 | -87627413666 |
| 16 | 1616831255645 |
| 17 | 95461592201461 |
| 18 | 5420484489890376 |
| 19 | -308006807300556157 |
| 20 | 18159275356643111275 |
| 21 | 3018684797307268036418 |