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 | 2 |
| 3 | 7 |
| 4 | 32 |
| 5 | 141 |
| 6 | -48 |
| 7 | -20509 |
| 8 | -572416 |
| 9 | -13236455 |
| 10 | -290711040 |
| 11 | -6196120193 |
| 12 | -125279895552 |
| 13 | -2200506714587 |
| 14 | -21844509804544 |
| 15 | 731664799971163 |
| 16 | 69257460487553024 |
| 17 | 3772508483052129329 |
| 18 | 174474102931077464064 |
| 19 | 7365599642083503837175 |
| 20 | 286164434343334028247040 |