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 | 6 |
| 2 | 40 |
| 3 | 288 |
| 4 | 2176 |
| 5 | 16896 |
| 6 | 133120 |
| 7 | 1056768 |
| 8 | 8421376 |
| 9 | 67239936 |
| 10 | 537395200 |
| 11 | 4297064448 |
| 12 | 34368126976 |
| 13 | 274911461376 |
| 14 | 2199157473280 |
| 15 | 17592722915328 |
| 16 | 140739635838976 |
| 17 | 1125908496777216 |
| 18 | 9007233614479360 |
| 19 | 72057731476881408 |