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 | 3 |
| 2 | 12 |
| 3 | 57 |
| 4 | 294 |
| 5 | 1578 |
| 6 | 8658 |
| 7 | 48177 |
| 8 | 270774 |
| 9 | 1533450 |
| 10 | 8736432 |
| 11 | 50016090 |
| 12 | 287497380 |
| 13 | 1658174352 |
| 14 | 9591422286 |
| 15 | 55618701057 |
| 16 | 323225066790 |
| 17 | 1882009941570 |
| 18 | 10976834700792 |
| 19 | 64119701075886 |
| 20 | 375057555388884 |
| 21 | 2196539772794172 |
| 22 | 12878508015774468 |