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 | -5 |
| 3 | 40 |
| 4 | -319 |
| 5 | 2908 |
| 6 | -28151 |
| 7 | 284908 |
| 8 | -2977115 |
| 9 | 31875709 |
| 10 | -347884084 |
| 11 | 3855802690 |
| 12 | -43283239649 |
| 13 | 491083601339 |
| 14 | -5622489637406 |
| 15 | 64877058557080 |
| 16 | -753705528179423 |
| 17 | 8808460811302729 |
| 18 | -103487549564845199 |
| 19 | 1221565052783161764 |
| 20 | -14480208437556590345 |