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) |
|---|---|
| 4 | 2 |
| 5 | 28 |
| 6 | 182 |
| 7 | 864 |
| 8 | 3474 |
| 9 | 12660 |
| 10 | 43358 |
| 11 | 142552 |
| 12 | 455930 |
| 13 | 1430796 |
| 14 | 4431078 |
| 15 | 13595664 |
| 16 | 41441570 |
| 17 | 125732836 |
| 18 | 380212142 |
| 19 | 1147057800 |
| 20 | 3454803594 |
| 21 | 10393245180 |
| 22 | 31240551350 |
| 23 | 93849578560 |
| 24 | 281817169202 |
| 25 | 846013542228 |
| 26 | 2539215029502 |
| 27 | 7620094559544 |
| 28 | 22865383949594 |