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 | 0 |
| 1 | 3 |
| 2 | 15 |
| 3 | 95 |
| 4 | 669 |
| 5 | 5133 |
| 6 | 41538 |
| 7 | 348513 |
| 8 | 3001134 |
| 9 | 26355867 |
| 10 | 234954223 |
| 11 | 2119654578 |
| 12 | 19308136142 |
| 13 | 177291661649 |
| 14 | 1638923764567 |
| 15 | 15237833654620 |
| 16 | 142377417196364 |
| 17 | 1336094767763971 |
| 18 | 12585956566571620 |
| 19 | 118959989688273472 |
| 20 | 1127779923790184543 |
| 21 | 10720710117789005897 |