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 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 6 |
| 5 | 14 |
| 6 | 39 |
| 7 | 125 |
| 8 | 399 |
| 9 | 1310 |
| 10 | 4356 |
| 11 | 14970 |
| 12 | 51715 |
| 13 | 178832 |
| 14 | 635778 |
| 15 | 2290019 |
| 16 | 8106059 |
| 17 | 29234378 |
| 18 | 105635076 |
| 19 | 384409483 |
| 20 | 1408730050 |
| 21 | 5193316109 |
| 22 | 19170300330 |
| 23 | 71421970661 |
| 24 | 263893092145 |
| 25 | 984568438169 |
| 26 | 3686368605467 |
| 27 | 13838552783467 |
| 28 | 52008816746450 |