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 | -15 |
| 3 | 47 |
| 4 | 1185 |
| 5 | -6241 |
| 6 | -230895 |
| 7 | 1704527 |
| 8 | 83860545 |
| 9 | -796079041 |
| 10 | -48942778575 |
| 11 | 567864586607 |
| 12 | 41893214676705 |
| 13 | -574448847467041 |
| 14 | -49441928730798255 |
| 15 | 782259922208550287 |
| 16 | 76946148390480577665 |
| 17 | -1379749466246228538241 |
| 18 | -152682246738275154625935 |