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 | 8 |
| 3 | 34 |
| 4 | 162 |
| 5 | 820 |
| 6 | 4338 |
| 7 | 23694 |
| 8 | 132612 |
| 9 | 756594 |
| 10 | 4384022 |
| 11 | 25729336 |
| 12 | 152627730 |
| 13 | 913674362 |
| 14 | 5512542128 |
| 15 | 33486653154 |
| 16 | 204639278346 |
| 17 | 1257199799116 |
| 18 | 7760098104882 |
| 19 | 48102326710998 |
| 20 | 299309479778956 |
| 21 | 1868853597670754 |