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 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 52 |
| 6 | 208 |
| 7 | 800 |
| 8 | 3360 |
| 9 | 16224 |
| 10 | 78088 |
| 11 | 393408 |
| 12 | 2189872 |
| 13 | 12371616 |
| 14 | 71835000 |
| 15 | 448860480 |
| 16 | 2871278464 |
| 17 | 18727425440 |
| 18 | 129070035784 |
| 19 | 913845701344 |