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 | 0 |
| 1 | 1 |
| 2 | 4112 |
| 3 | 531522 |
| 4 | 16843008 |
| 5 | 244141250 |
| 6 | 2185618464 |
| 7 | 13841289602 |
| 8 | 68988964864 |
| 9 | 282472589763 |
| 10 | 1003908820000 |
| 11 | 3138428391362 |
| 12 | 8952429298176 |
| 13 | 23298085151042 |
| 14 | 56915382843424 |
| 15 | 129766445482500 |
| 16 | 282578800148480 |
| 17 | 582622237313282 |
| 18 | 1161527289105456 |
| 19 | 2213314919196482 |
| 20 | 4112073026880000 |