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 | 115 |
| 6 | 609 |
| 7 | 3409 |
| 8 | 19728 |
| 9 | 116692 |
| 10 | 701062 |
| 11 | 4261581 |
| 12 | 26146111 |
| 13 | 161631115 |
| 14 | 1005522262 |
| 15 | 6289410686 |
| 16 | 39525228204 |
| 17 | 249427451071 |
| 18 | 1579885391573 |
| 19 | 10040587733693 |
| 20 | 64004713573508 |
| 21 | 409139527503760 |
| 22 | 2622049900367018 |
| 23 | 16843666877986873 |
| 24 | 108438876033442579 |