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 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 40 |
| 6 | 116 |
| 7 | 200 |
| 8 | 444 |
| 9 | 864 |
| 10 | 3368 |
| 11 | 10936 |
| 12 | 38320 |
| 13 | 139848 |
| 14 | 534828 |
| 15 | 2230464 |
| 16 | 9802612 |
| 17 | 46188544 |
| 18 | 231210272 |
| 19 | 1213437504 |
| 20 | 6717614708 |
| 21 | 39002297800 |