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 | 9 |
| 4 | 33 |
| 5 | 141 |
| 6 | 651 |
| 7 | 3333 |
| 8 | 18369 |
| 9 | 108153 |
| 10 | 678771 |
| 11 | 4495041 |
| 12 | 31324833 |
| 13 | 228803589 |
| 14 | 1744475643 |
| 15 | 13852095741 |
| 16 | 114235118721 |
| 17 | 976176336753 |
| 18 | 8627940414819 |
| 19 | 78726234866553 |
| 20 | 740440277799201 |
| 21 | 7168107030092541 |
| 22 | 71331617341611243 |
| 23 | 728811735008913909 |
| 24 | 7637128289949856833 |
| 25 | 81995144342947130601 |