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 | -20 |
| 4 | 66 |
| 5 | 4439 |
| 6 | 454420 |
| 7 | 4873175 |
| 8 | -3803048954 |
| 9 | -7320203267692 |
| 10 | -1403057989033446 |
| 11 | 6669491545211096686 |
| 12 | 78492109668913945526447 |
| 13 | 69591502229308312804788424 |
| 14 | -6243846072108996200105800383026 |
| 15 | -604234376454072219680822138902122079 |