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 | 12 |
| 2 | 56 |
| 3 | 232 |
| 4 | 988 |
| 5 | 4180 |
| 6 | 17712 |
| 7 | 75024 |
| 8 | 317812 |
| 9 | 1346268 |
| 10 | 5702888 |
| 11 | 24157816 |
| 12 | 102334156 |
| 13 | 433494436 |
| 14 | 1836311904 |
| 15 | 7778742048 |
| 16 | 32951280100 |
| 17 | 139583862444 |
| 18 | 591286729880 |
| 19 | 2504730781960 |
| 20 | 10610209857724 |
| 21 | 44945570212852 |