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 | 16 |
| 3 | 96 |
| 4 | 512 |
| 5 | 2560 |
| 6 | 24576 |
| 7 | 229376 |
| 8 | 2097152 |
| 9 | 17956864 |
| 10 | 142606336 |
| 11 | 1107296256 |
| 12 | 8589934592 |
| 13 | 67612180480 |
| 14 | 541165879296 |
| 15 | 4363686772736 |
| 16 | 35184372088832 |
| 17 | 282583078273024 |
| 18 | 2260595906707456 |
| 19 | 18049582881570816 |
| 20 | 144115188075855872 |
| 21 | 1151793405676748800 |