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 | 10 |
| 3 | 68 |
| 4 | 502 |
| 5 | 3770 |
| 6 | 28408 |
| 7 | 214202 |
| 8 | 1615330 |
| 9 | 12181748 |
| 10 | 91867102 |
| 11 | 692804690 |
| 12 | 5224704088 |
| 13 | 39401485202 |
| 14 | 297141621850 |
| 15 | 2240858259428 |
| 16 | 16899166494502 |
| 17 | 127443057596810 |
| 18 | 961096686931768 |
| 19 | 7247996548821002 |
| 20 | 54659905383139570 |