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 | 3 |
| 3 | 7 |
| 4 | 21 |
| 5 | 71 |
| 6 | 253 |
| 7 | 925 |
| 8 | 3433 |
| 9 | 12871 |
| 10 | 48621 |
| 11 | 184757 |
| 12 | 705433 |
| 13 | 2704157 |
| 14 | 10400601 |
| 15 | 40116601 |
| 16 | 155117521 |
| 17 | 601080391 |
| 18 | 2333606221 |
| 19 | 9075135301 |
| 20 | 35345263801 |
| 21 | 137846528821 |
| 22 | 538257874441 |
| 23 | 2104098963721 |
| 24 | 8233430727601 |
| 25 | 32247603683101 |
| 26 | 126410606437753 |
| 27 | 495918532948105 |