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 | 36 |
| 4 | 176 |
| 5 | 912 |
| 6 | 4928 |
| 7 | 27472 |
| 8 | 156864 |
| 9 | 912832 |
| 10 | 5394176 |
| 11 | 32282240 |
| 12 | 195264000 |
| 13 | 1191825920 |
| 14 | 7331457024 |
| 15 | 45406194944 |
| 16 | 282896763904 |
| 17 | 1771868302336 |
| 18 | 11150040870912 |
| 19 | 70461597988864 |
| 20 | 446971590516736 |
| 21 | 2845144452292608 |