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 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 36 |
| 5 | 120 |
| 6 | 400 |
| 7 | 1520 |
| 8 | 5776 |
| 9 | 23712 |
| 10 | 97344 |
| 11 | 431808 |
| 12 | 1915456 |
| 13 | 9012608 |
| 14 | 42406144 |
| 15 | 210988800 |
| 16 | 1049760000 |
| 17 | 5475340800 |
| 18 | 28558296064 |
| 19 | 155672726528 |
| 20 | 848579961856 |
| 21 | 4810614454272 |
| 22 | 27271456395264 |
| 23 | 160376430784512 |
| 24 | 943132599095296 |
| 25 | 5735299537018880 |