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) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 22 |
| 4 | 154 |
| 5 | 548 |
| 6 | 7488 |
| 7 | 26136 |
| 8 | 471168 |
| 9 | 3272832 |
| 10 | 46114560 |
| 11 | 241087680 |
| 12 | 10152587520 |
| 13 | 39605518080 |
| 14 | 1245053859840 |
| 15 | 19626466406400 |
| 16 | 402874746624000 |
| 17 | 2446811181158400 |
| 18 | 156604969130803200 |
| 19 | 863130293635276800 |
| 20 | 62029933697765376000 |
| 21 | 858218507492806656000 |