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 | -2 |
| 2 | 14 |
| 3 | -156 |
| 4 | 2328 |
| 5 | -42630 |
| 6 | 902736 |
| 7 | -20961864 |
| 8 | 497925504 |
| 9 | -10347816906 |
| 10 | 54902188800 |
| 11 | 15803663268492 |
| 12 | -1741565563831296 |
| 13 | 146556727320337074 |
| 14 | -11551833579195721728 |
| 15 | 901051402625901468000 |
| 16 | -71007771313742983888896 |
| 17 | 5701873713553516375488366 |
| 18 | -467924697090124685492944896 |