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 | 2064 |
| 3 | 177228 |
| 4 | 4227328 |
| 5 | 48828750 |
| 6 | 365798592 |
| 7 | 1977329144 |
| 8 | 8657571840 |
| 9 | 31395415077 |
| 10 | 100782540000 |
| 11 | 285311685252 |
| 12 | 749200886784 |
| 13 | 1792160422598 |
| 14 | 4081207353216 |
| 15 | 8653821705000 |
| 16 | 17730707193856 |
| 17 | 34271896391154 |
| 18 | 64800136718928 |
| 19 | 116490259028540 |
| 20 | 206415142080000 |
| 21 | 350438089532832 |