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) |
|---|---|
| 1 | 4 |
| 2 | 12 |
| 3 | 80 |
| 4 | 448 |
| 5 | 11264 |
| 6 | 53248 |
| 7 | 1114112 |
| 8 | 4980736 |
| 9 | 96468992 |
| 10 | 7784628224 |
| 11 | 33285996544 |
| 12 | 2542620639232 |
| 13 | 45079976738816 |
| 14 | 189115999977472 |
| 15 | 3307330976350208 |
| 16 | 238690780250636288 |
| 17 | 17005592192950992896 |
| 18 | 70328211781017665536 |
| 19 | 4943727411754159833088 |
| 20 | 83822005070936202543104 |