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 | 5 |
| 2 | 26 |
| 3 | 139 |
| 4 | 757 |
| 5 | 4172 |
| 6 | 23165 |
| 7 | 129217 |
| 8 | 722818 |
| 9 | 4050239 |
| 10 | 22718609 |
| 11 | 127512940 |
| 12 | 715962889 |
| 13 | 4020920141 |
| 14 | 22584986378 |
| 15 | 126867394723 |
| 16 | 712691811325 |
| 17 | 4003745802188 |
| 18 | 22492567804517 |
| 19 | 126361939999081 |
| 20 | 709898671705906 |
| 21 | 3988211185370615 |
| 22 | 22405825905923321 |
| 23 | 125876420631268204 |