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 | 2 |
| 2 | 9 |
| 3 | 46 |
| 4 | 253 |
| 5 | 1452 |
| 6 | 8570 |
| 7 | 51594 |
| 8 | 315225 |
| 9 | 1948010 |
| 10 | 12147881 |
| 11 | 76316508 |
| 12 | 482392198 |
| 13 | 3064987460 |
| 14 | 19560379470 |
| 15 | 125309993974 |
| 16 | 805458510441 |
| 17 | 5192500350906 |
| 18 | 33561539356277 |
| 19 | 217429403317006 |
| 20 | 1411572472199649 |
| 21 | 9181398851046632 |
| 22 | 59821825063376124 |
| 23 | 390382132833183204 |