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 | 5 |
| 2 | 17 |
| 3 | 63 |
| 4 | 227 |
| 5 | 827 |
| 6 | 2999 |
| 7 | 10897 |
| 8 | 39561 |
| 9 | 143677 |
| 10 | 521721 |
| 11 | 1894607 |
| 12 | 6879979 |
| 13 | 24983923 |
| 14 | 90725999 |
| 15 | 329460929 |
| 16 | 1196397873 |
| 17 | 4344577397 |
| 18 | 15776816033 |
| 19 | 57291635519 |
| 20 | 208047769363 |
| 21 | 755500774443 |
| 22 | 2743511349031 |
| 23 | 9962735709201 |
| 24 | 36178491743225 |
| 25 | 131377896967213 |
| 26 | 477083233044745 |