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 | 4 |
| 2 | 16 |
| 3 | 44 |
| 4 | 160 |
| 5 | 556 |
| 6 | 1744 |
| 7 | 12252 |
| 8 | 15840 |
| 9 | 98876 |
| 10 | 138160 |
| 11 | 709900 |
| 12 | 1155616 |
| 13 | 5098260 |
| 14 | 11820656 |
| 15 | 37085908 |
| 16 | 111147104 |
| 17 | 281078764 |
| 18 | 932893104 |
| 19 | 2255139900 |
| 20 | 7295211968 |
| 21 | 18928121236 |
| 22 | 54864568720 |
| 23 | 160016686500 |
| 24 | 404167501888 |
| 25 | 1331607134172 |
| 26 | 2945597090384 |
| 27 | 10805511468852 |
| 28 | 21448743511648 |