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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -10 |
| 4 | 10 |
| 5 | 190 |
| 6 | -730 |
| 7 | -6620 |
| 8 | 55900 |
| 9 | 365300 |
| 10 | -5864300 |
| 11 | -28269800 |
| 12 | 839594600 |
| 13 | 2691559000 |
| 14 | -159300557000 |
| 15 | -238131478000 |
| 16 | 38894192662000 |
| 17 | -15194495654000 |
| 18 | -11911522255750000 |
| 19 | 29697351895900000 |
| 20 | 4477959179352100000 |
| 21 | -21683886333440500000 |
| 22 | -2029107997508660900000 |
| 23 | 15145164178973569000000 |