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 | 3 |
| 2 | 15 |
| 3 | 99 |
| 4 | 495 |
| 5 | 2079 |
| 6 | 4455 |
| 7 | 36855 |
| 8 | 70875 |
| 9 | 280665 |
| 10 | 1393119 |
| 11 | 4179357 |
| 12 | 12931731 |
| 13 | 32417901 |
| 14 | 161026623 |
| 15 | 514966329 |
| 16 | 1490692005 |