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 | 5 |
| 3 | 20 |
| 4 | 100 |
| 5 | 480 |
| 6 | 1980 |
| 7 | 7680 |
| 8 | 29040 |
| 9 | 100920 |
| 10 | 316320 |
| 11 | 923520 |
| 12 | 2502000 |
| 13 | 6011760 |
| 14 | 12584880 |
| 15 | 23417280 |
| 16 | 38196480 |
| 17 | 50112000 |
| 18 | 53667840 |
| 19 | 64988160 |
| 20 | 64988160 |