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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 4 |
| 6 | 14 |
| 7 | 52 |
| 8 | 201 |
| 9 | 792 |
| 10 | 3168 |
| 11 | 12844 |
| 12 | 52676 |
| 13 | 218148 |
| 14 | 910996 |
| 15 | 3832072 |
| 16 | 16222352 |
| 17 | 69061200 |
| 18 | 295477550 |
| 19 | 1269863304 |
| 20 | 5479456290 |
| 21 | 23730089460 |
| 22 | 103109502780 |
| 23 | 449376255840 |
| 24 | 1963920878400 |
| 25 | 8604858967692 |
| 26 | 37790621078040 |
| 27 | 166329352089096 |
| 28 | 733551460238308 |