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 | 1 |
| 2 | 8 |
| 3 | 48 |
| 4 | 344 |
| 5 | 2460 |
| 6 | 18152 |
| 7 | 134512 |
| 8 | 1012664 |
| 9 | 7635987 |
| 10 | 58199208 |
| 11 | 443658688 |
| 12 | 3409213016 |
| 13 | 26184550496 |
| 14 | 202384723528 |
| 15 | 1562970918720 |
| 16 | 12133130451576 |
| 17 | 94094281551304 |
| 18 | 732910480638272 |
| 19 | 5702603044247504 |
| 20 | 44538031693977544 |