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 | 2 |
| 3 | 12 |
| 4 | 48 |
| 5 | 240 |
| 6 | 2160 |
| 7 | 15120 |
| 8 | 120960 |
| 9 | 1451520 |
| 10 | 14515200 |
| 11 | 159667200 |
| 12 | 2395008000 |
| 13 | 31135104000 |
| 14 | 435891456000 |
| 15 | 7846046208000 |
| 16 | 125536739328000 |
| 17 | 2134124568576000 |
| 18 | 44816615940096000 |
| 19 | 851515702861824000 |