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 | 1 |
| 2 | 10 |
| 3 | 162 |
| 4 | 280 |
| 5 | 12320 |
| 6 | 524880 |
| 7 | 1106560 |
| 8 | 96342400 |
| 9 | 7142567040 |
| 10 | 17041024000 |
| 11 | 2324549427200 |
| 12 | 254561089305600 |
| 13 | 664565853952000 |
| 14 | 126757680265216000 |
| 15 | 18763697892715776000 |
| 16 | 52580450364682240000 |
| 17 | 13106744139423334400000 |
| 18 | 2480410751833883860992000 |