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 | 1 |
| 2 | 6 |
| 3 | 114 |
| 4 | 5256 |
| 5 | 507720 |
| 6 | 93616560 |
| 7 | 30894489360 |
| 8 | 17407086641280 |
| 9 | 16152167106391680 |
| 10 | 23990233574783750400 |
| 11 | 55735096448700749203200 |
| 12 | 198720975339675515386598400 |
| 13 | 1070118060127292955589511500800 |
| 14 | 8585695098723146508385537345689600 |
| 15 | 101432601341702692223559539854263552000 |