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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 6 |
| 5 | 44 |
| 6 | 66 |
| 7 | 252 |
| 8 | 2112 |
| 9 | 2772 |
| 10 | 6336 |
| 11 | 27972 |
| 12 | 48384 |
| 13 | 219912 |
| 14 | 252252 |
| 15 | 696696 |
| 16 | 828828 |
| 17 | 2114112 |
| 18 | 4228224 |
| 19 | 21333312 |
| 20 | 42666624 |
| 21 | 63999936 |
| 22 | 234666432 |
| 23 | 2154664512 |
| 24 | 2329559232 |
| 25 | 4815995184 |
| 26 | 8402442048 |
| 27 | 21354645312 |
| 28 | 40362626304 |
| 29 | 63708380736 |
| 30 | 211887788112 |