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 | 36 |
| 3 | 208 |
| 4 | 1200 |
| 5 | 6912 |
| 6 | 39808 |
| 7 | 229248 |
| 8 | 1320192 |
| 9 | 7602688 |
| 10 | 43782144 |
| 11 | 252131328 |
| 12 | 1451966464 |
| 13 | 8361541632 |
| 14 | 48152199168 |
| 15 | 277297463296 |
| 16 | 1596892446720 |
| 17 | 9196137086976 |
| 18 | 52958442815488 |
| 19 | 304975517319168 |
| 20 | 1756284007219200 |