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 | 4 |
| 3 | 15 |
| 4 | 56 |
| 5 | 209 |
| 6 | 780 |
| 7 | 2912 |
| 8 | 10880 |
| 9 | 40698 |
| 10 | 152456 |
| 11 | 572033 |
| 12 | 2150040 |
| 13 | 8095425 |
| 14 | 30535260 |
| 15 | 115377660 |
| 16 | 436698240 |
| 17 | 1655607390 |
| 18 | 6286707000 |
| 19 | 23908446510 |
| 20 | 91057063344 |
| 21 | 347281885818 |
| 22 | 1326262602104 |
| 23 | 5071418015120 |
| 24 | 19415851639296 |
| 25 | 74419447792340 |