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 | 4 |
| 2 | 16 |
| 3 | 68 |
| 4 | 288 |
| 5 | 1216 |
| 6 | 5136 |
| 7 | 21696 |
| 8 | 91648 |
| 9 | 387136 |
| 10 | 1635328 |
| 11 | 6907904 |
| 12 | 29180160 |
| 13 | 123261952 |
| 14 | 520679424 |
| 15 | 2199438336 |
| 16 | 9290801152 |
| 17 | 39245922304 |
| 18 | 165781442560 |
| 19 | 700288974848 |
| 20 | 2958139588608 |
| 21 | 12495684124672 |
| 22 | 52783892398080 |