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 | 2 |
| 2 | 12 |
| 3 | 52 |
| 4 | 212 |
| 5 | 852 |
| 6 | 3412 |
| 7 | 13652 |
| 8 | 54612 |
| 9 | 218452 |
| 10 | 873812 |
| 11 | 3495252 |
| 12 | 13981012 |
| 13 | 55924052 |
| 14 | 223696212 |
| 15 | 894784852 |
| 16 | 3579139412 |
| 17 | 14316557652 |
| 18 | 57266230612 |
| 19 | 229064922452 |
| 20 | 916259689812 |
| 21 | 3665038759252 |
| 22 | 14660155037012 |
| 23 | 58640620148052 |
| 24 | 234562480592212 |
| 25 | 938249922368852 |