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 | 6 |
| 1 | 6 |
| 2 | 11 |
| 3 | 31 |
| 4 | 121 |
| 5 | 601 |
| 6 | 3601 |
| 7 | 25201 |
| 8 | 201601 |
| 9 | 1814401 |
| 10 | 18144001 |
| 11 | 199584001 |
| 12 | 2395008001 |
| 13 | 31135104001 |
| 14 | 435891456001 |
| 15 | 6538371840001 |
| 16 | 104613949440001 |
| 17 | 1778437140480001 |
| 18 | 32011868528640001 |
| 19 | 608225502044160001 |
| 20 | 12164510040883200001 |
| 21 | 255454710858547200001 |