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 | 181 |
| 6 | 603 |
| 7 | 1933 |
| 8 | 6051 |
| 9 | 18661 |
| 10 | 57003 |
| 11 | 173053 |
| 12 | 523251 |
| 13 | 1577941 |
| 14 | 4750203 |
| 15 | 14283373 |
| 16 | 42915651 |
| 17 | 128878021 |
| 18 | 386896203 |
| 19 | 1161212893 |
| 20 | 3484687251 |
| 21 | 10456158901 |
| 22 | 31372671003 |
| 23 | 94126401613 |
| 24 | 282395982051 |
| 25 | 847221500581 |