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 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 65 |
| 6 | 216 |
| 7 | 728 |
| 8 | 2472 |
| 9 | 8451 |
| 10 | 29050 |
| 11 | 100298 |
| 12 | 347568 |
| 13 | 1208220 |
| 14 | 4211312 |
| 15 | 14712960 |
| 16 | 51507280 |
| 17 | 180642391 |
| 18 | 634551606 |
| 19 | 2232223626 |
| 20 | 7862669700 |
| 21 | 27727507521 |
| 22 | 97884558992 |
| 23 | 345891702456 |
| 24 | 1223358393120 |
| 25 | 4330360551700 |