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 | 3 |
| 1 | 13 |
| 2 | 53 |
| 3 | 213 |
| 4 | 853 |
| 5 | 3413 |
| 6 | 13653 |
| 7 | 54613 |
| 8 | 218453 |
| 9 | 873813 |
| 10 | 3495253 |
| 11 | 13981013 |
| 12 | 55924053 |
| 13 | 223696213 |
| 14 | 894784853 |
| 15 | 3579139413 |
| 16 | 14316557653 |
| 17 | 57266230613 |
| 18 | 229064922453 |
| 19 | 916259689813 |
| 20 | 3665038759253 |
| 21 | 14660155037013 |
| 22 | 58640620148053 |
| 23 | 234562480592213 |
| 24 | 938249922368853 |
| 25 | 3752999689475413 |