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 | 10 |
| 5 | 10 |
| 6 | -97 |
| 7 | -638 |
| 8 | -1316 |
| 9 | 9908 |
| 10 | 118713 |
| 11 | 560533 |
| 12 | -697429 |
| 13 | -38229322 |
| 14 | -364288567 |
| 15 | -1441996161 |
| 16 | 11586777849 |
| 17 | 281338444108 |
| 18 | 2772828770441 |
| 19 | 10249821640498 |
| 20 | -170439385810217 |
| 21 | -4104012197171264 |
| 22 | -46232949019802137 |
| 23 | -204897893603728741 |
| 24 | 3708422726478663919 |