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 | 3 |
| 2 | -30 |
| 3 | 105 |
| 4 | -1260 |
| 5 | 3465 |
| 6 | -18018 |
| 7 | 45045 |
| 8 | -875160 |
| 9 | 2078505 |
| 10 | -9699690 |
| 11 | 22309287 |
| 12 | -202811700 |
| 13 | 456326325 |
| 14 | -2035917450 |
| 15 | 4508102925 |
| 16 | -158685222960 |
| 17 | 347123925225 |
| 18 | -1511010027450 |
| 19 | 3273855059475 |
| 20 | -28258538408100 |