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 | 3 |
| 2 | 15 |
| 3 | 105 |
| 4 | 315 |
| 5 | 3465 |
| 6 | 45045 |
| 7 | 45045 |
| 8 | 765765 |
| 9 | 14549535 |
| 10 | 14549535 |
| 11 | 334639305 |
| 12 | 1673196525 |
| 13 | 5019589575 |
| 14 | 145568097675 |
| 15 | 4512611027925 |
| 16 | 4512611027925 |
| 17 | 4512611027925 |
| 18 | 166966608033225 |
| 19 | 166966608033225 |
| 20 | 6845630929362225 |
| 21 | 294362129962575675 |
| 22 | 294362129962575675 |
| 23 | 13835020108241056725 |