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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 51 |
| 5 | 206 |
| 6 | 855 |
| 7 | 3585 |
| 8 | 15155 |
| 9 | 64525 |
| 10 | 276278 |
| 11 | 1188353 |
| 12 | 5130999 |
| 13 | 22226049 |
| 14 | 96544003 |
| 15 | 420368858 |
| 16 | 1834203955 |
| 17 | 8018057345 |
| 18 | 35107961175 |
| 19 | 153950675585 |
| 20 | 675978772326 |
| 21 | 2971700764941 |
| 22 | 13078268135683 |
| 23 | 57613905606273 |
| 24 | 254038914924791 |
| 25 | 1121081799217231 |