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 | 5 |
| 2 | 22 |
| 3 | 102 |
| 4 | 510 |
| 5 | 3210 |
| 6 | 17490 |
| 7 | 112890 |
| 8 | 600270 |
| 9 | 3466470 |
| 10 | 20205570 |
| 11 | 118879530 |
| 12 | 697118730 |
| 13 | 3949737330 |
| 14 | 24217298490 |
| 15 | 143487592710 |
| 16 | 841422307110 |
| 17 | 4973562896610 |
| 18 | 29520886859310 |
| 19 | 180254162529210 |
| 20 | 1052751138726210 |
| 21 | 6301225298627490 |
| 22 | 37854941354933010 |
| 23 | 224270177470178070 |