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 | 3 |
| 3 | 7 |
| 4 | 35 |
| 5 | 155 |
| 6 | 1395 |
| 7 | 11811 |
| 8 | 200787 |
| 9 | 3309747 |
| 10 | 109221651 |
| 11 | 3548836819 |
| 12 | 230674393235 |
| 13 | 14877590196755 |
| 14 | 1919209135381395 |
| 15 | 246614610741341843 |
| 16 | 63379954960524853651 |
| 17 | 16256896431763117598611 |
| 18 | 8339787869494479328087443 |
| 19 | 4274137206973266943778085267 |