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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 21 |
| 5 | 73 |
| 6 | 255 |
| 7 | 946 |
| 8 | 3618 |
| 9 | 14376 |
| 10 | 58957 |
| 11 | 249555 |
| 12 | 1087828 |
| 13 | 4878939 |
| 14 | 22488282 |
| 15 | 106432530 |
| 16 | 516783762 |
| 17 | 2572324160 |
| 18 | 13116137104 |
| 19 | 68461594211 |
| 20 | 365559412868 |
| 21 | 1995532789212 |
| 22 | 11129600885183 |
| 23 | 63381069498524 |
| 24 | 368338847181336 |
| 25 | 2183239817036378 |