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) |
|---|---|
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 6 |
| 6 | 25 |
| 7 | 105 |
| 8 | 490 |
| 9 | 2548 |
| 10 | 14698 |
| 11 | 93420 |
| 12 | 649715 |
| 13 | 4912776 |
| 14 | 40154387 |
| 15 | 352937312 |
| 16 | 3320636540 |
| 17 | 33305992320 |
| 18 | 354819046132 |
| 19 | 4001699525376 |
| 20 | 47637151241125 |
| 21 | 596958623741440 |
| 22 | 7855611484697773 |
| 23 | 108314507544748032 |
| 24 | 1561635447992241230 |
| 25 | 23498865431367684096 |