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 | 3 |
| 3 | 12 |
| 4 | 28 |
| 5 | 168 |
| 6 | 546 |
| 7 | 4368 |
| 8 | 9360 |
| 9 | 28800 |
| 10 | 148800 |
| 11 | 1785600 |
| 12 | 5401440 |
| 13 | 75620160 |
| 14 | 538793640 |
| 15 | 2711348640 |
| 16 | 5603453856 |
| 17 | 100862169408 |
| 18 | 303420079872 |
| 19 | 6068401597440 |
| 20 | 30380907997440 |
| 21 | 213199354368000 |
| 22 | 2362959510912000 |
| 23 | 56711028261888000 |
| 24 | 170288884313856000 |