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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 68 |
| 5 | 304 |
| 6 | 1412 |
| 7 | 6752 |
| 8 | 33028 |
| 9 | 164512 |
| 10 | 831620 |
| 11 | 4255728 |
| 12 | 22004292 |
| 13 | 114781008 |
| 14 | 603308292 |
| 15 | 3192216000 |
| 16 | 16989553668 |
| 17 | 90890869312 |
| 18 | 488500827908 |
| 19 | 2636405463248 |
| 20 | 14281895003716 |
| 21 | 77631035881072 |
| 22 | 423282220216964 |
| 23 | 2314491475510816 |
| 24 | 12688544297945348 |