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 | 3 |
| 1 | 66 |
| 2 | 1050 |
| 3 | 15300 |
| 4 | 220500 |
| 5 | 3245760 |
| 6 | 49533120 |
| 7 | 789264000 |
| 8 | 13172544000 |
| 9 | 230519520000 |
| 10 | 4229703878400 |
| 11 | 81315551116800 |
| 12 | 1636227552960000 |
| 13 | 34417989365760000 |
| 14 | 755835784704000000 |
| 15 | 17305616126582784000 |
| 16 | 412559358036553728000 |
| 17 | 10227311816872550400000 |
| 18 | 263309943217447526400000 |
| 19 | 7032029553158658048000000 |