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 | 1 |
| 2 | 6 |
| 3 | 28 |
| 4 | 120 |
| 5 | 496 |
| 6 | 672 |
| 7 | 8128 |
| 8 | 523776 |
| 9 | 33550336 |
| 10 | 1379454720 |
| 11 | 8589869056 |
| 12 | 137438691328 |
| 13 | 2305843008139952128 |
| 14 | 203820700083634254643200 |
| 15 | 2658455991569831744654692615953842176 |