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 | 24 |
| 5 | 96 |
| 6 | 384 |
| 7 | 1374 |
| 8 | 4718 |
| 9 | 16275 |
| 10 | 57749 |
| 11 | 206756 |
| 12 | 739780 |
| 13 | 2637348 |
| 14 | 9378840 |
| 15 | 33318804 |
| 16 | 118439044 |
| 17 | 421340612 |
| 18 | 1499388117 |
| 19 | 5335199213 |
| 20 | 18980987054 |
| 21 | 67522942850 |
| 22 | 240204885524 |
| 23 | 854523535096 |
| 24 | 3040023558788 |
| 25 | 10815153542594 |