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 | 18 |
| 5 | 100 |
| 6 | 665 |
| 7 | 5124 |
| 8 | 44772 |
| 9 | 437016 |
| 10 | 4710915 |
| 11 | 55568480 |
| 12 | 711802894 |
| 13 | 9838192572 |
| 14 | 145921265581 |
| 15 | 2311617527660 |
| 16 | 38950657146120 |
| 17 | 695562375445104 |
| 18 | 13121344429311687 |
| 19 | 260728755911619336 |
| 20 | 5443039353326333330 |
| 21 | 119101575356825879860 |
| 22 | 2725785134463572716689 |