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 | 2 |
| 2 | 9 |
| 3 | 51 |
| 4 | 324 |
| 5 | 2206 |
| 6 | 15737 |
| 7 | 116098 |
| 8 | 878495 |
| 9 | 6780544 |
| 10 | 53175176 |
| 11 | 422508607 |
| 12 | 3394004192 |
| 13 | 27518168434 |
| 14 | 224899980185 |
| 15 | 1850830170355 |
| 16 | 15324273361220 |
| 17 | 127562500961502 |
| 18 | 1066940307951747 |
| 19 | 8962213871074848 |
| 20 | 75572666059970392 |
| 21 | 639485384767169924 |
| 22 | 5428457500063304272 |