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) |
|---|---|
| 2 | 120 |
| 3 | 4860 |
| 4 | 65280 |
| 5 | 487500 |
| 6 | 2517480 |
| 7 | 10084200 |
| 8 | 33546240 |
| 9 | 96840360 |
| 10 | 249975000 |
| 11 | 589446660 |
| 12 | 1289882880 |
| 13 | 2651032020 |
| 14 | 5165127240 |
| 15 | 9610650000 |
| 16 | 17179607040 |
| 17 | 29646614160 |
| 18 | 49589350200 |
| 19 | 80671305420 |
| 20 | 127999200000 |
| 21 | 198568990620 |
| 22 | 301816016040 |
| 23 | 450286556280 |
| 24 | 660449894400 |