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 | 3 |
| 2 | -48 |
| 3 | -665 |
| 4 | -3840 |
| 5 | -14601 |
| 6 | -42560 |
| 7 | -101265 |
| 8 | -196608 |
| 9 | -269297 |
| 10 | 48576 |
| 11 | 2422743 |
| 12 | 13791232 |
| 13 | 62282055 |
| 14 | 260905920 |
| 15 | 1062351199 |
| 16 | 4278190080 |
| 17 | 17155731615 |
| 18 | 68685464512 |
| 19 | 274830861063 |
| 20 | 1099447627776 |