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 | -3 |
| 3 | -1 |
| 4 | 41 |
| 5 | 239 |
| 6 | 229 |
| 7 | -8401 |
| 8 | -87151 |
| 9 | -324577 |
| 10 | 3238541 |
| 11 | 70271519 |
| 12 | 601086265 |
| 13 | 142860431 |
| 14 | -81504662539 |
| 15 | -1393683935281 |
| 16 | -10777424809951 |
| 17 | 63537986981183 |
| 18 | 3552608426329117 |
| 19 | 60283510555017023 |
| 20 | 441644419610814281 |
| 21 | -6191820436867600081 |