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 | 1 |
| 3 | 4 |
| 4 | 10 |
| 5 | 136 |
| 6 | 720 |
| 7 | 44224 |
| 8 | 703760 |
| 9 | 179228736 |
| 10 | 9168331776 |
| 11 | 9383939974144 |
| 12 | 1601371799340544 |
| 13 | 6558936236286040064 |
| 14 | 3837878966366932639744 |
| 15 | 62879572771326489528942592 |
| 16 | 128777257564337108286016980992 |