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 | 3 |
| 4 | 13 |
| 5 | 50 |
| 6 | 201 |
| 7 | 875 |
| 8 | 4138 |
| 9 | 21145 |
| 10 | 115973 |
| 11 | 678568 |
| 12 | 4213595 |
| 13 | 27644435 |
| 14 | 190899320 |
| 15 | 1382958543 |
| 16 | 10480142145 |
| 17 | 82864869802 |
| 18 | 682076806157 |
| 19 | 5832742205055 |
| 20 | 51724158235370 |
| 21 | 474869816156749 |
| 22 | 4506715738447321 |
| 23 | 44152005855084344 |
| 24 | 445958869294805287 |
| 25 | 4638590332229999351 |