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 | 56 |
| 4 | 268 |
| 5 | 1448 |
| 6 | 7864 |
| 7 | 42752 |
| 8 | 236368 |
| 9 | 1313696 |
| 10 | 7339552 |
| 11 | 41217920 |
| 12 | 232321984 |
| 13 | 1313731712 |
| 14 | 7449834880 |
| 15 | 42347380736 |
| 16 | 241225384192 |
| 17 | 1376662561280 |
| 18 | 7869527190016 |
| 19 | 45051709749248 |
| 20 | 258256281078784 |
| 21 | 1482218578159616 |