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 | 52 |
| 3 | 568 |
| 4 | 7312 |
| 5 | 107360 |
| 6 | 1760576 |
| 7 | 31760256 |
| 8 | 623137024 |
| 9 | 13179872768 |
| 10 | 298391335936 |
| 11 | 7189153167360 |
| 12 | 183428957442048 |
| 13 | 4935794590572544 |
| 14 | 139571328018628608 |
| 15 | 4134634425826115584 |
| 16 | 127966201403431518208 |
| 17 | 4127825849826169716736 |
| 18 | 138477447400991610896384 |
| 19 | 4822002684952714247929856 |