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) |
|---|---|
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 13 |
| 6 | 44 |
| 7 | 149 |
| 8 | 498 |
| 9 | 1656 |
| 10 | 5498 |
| 11 | 18236 |
| 12 | 60456 |
| 13 | 200409 |
| 14 | 664464 |
| 15 | 2203755 |
| 16 | 7311894 |
| 17 | 24271290 |
| 18 | 80605250 |
| 19 | 267821525 |
| 20 | 890305418 |
| 21 | 2961015981 |
| 22 | 9852481830 |
| 23 | 32798011430 |
| 24 | 109229396466 |
| 25 | 363927233758 |
| 26 | 1213012655490 |
| 27 | 4044684629394 |
| 28 | 13491663770344 |