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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 96 |
| 6 | 576 |
| 7 | 4032 |
| 8 | 32256 |
| 9 | 290304 |
| 10 | 2975616 |
| 11 | 32731776 |
| 12 | 392781312 |
| 13 | 5106157056 |
| 14 | 71486198784 |
| 15 | 1070549415936 |
| 16 | 17128790654976 |
| 17 | 291189441134592 |
| 18 | 5241409940422656 |
| 19 | 99586788868030464 |
| 20 | 1991897970827821056 |
| 21 | 41829857387384242176 |
| 22 | 920256862522453327872 |