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 | 35 |
| 4 | 315 |
| 5 | 693 |
| 6 | 3003 |
| 7 | 6435 |
| 8 | 109395 |
| 9 | 230945 |
| 10 | 969969 |
| 11 | 2028117 |
| 12 | 16900975 |
| 13 | 35102025 |
| 14 | 145422675 |
| 15 | 300540195 |
| 16 | 9917826435 |
| 17 | 20419054425 |
| 18 | 83945001525 |
| 19 | 172308161025 |
| 20 | 1412926920405 |
| 21 | 2893136075115 |
| 22 | 11835556670925 |