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 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 66 |
| 6 | 229 |
| 7 | 831 |
| 8 | 2991 |
| 9 | 10859 |
| 10 | 39173 |
| 11 | 141631 |
| 12 | 510079 |
| 13 | 1835583 |
| 14 | 6586932 |
| 15 | 23614821 |
| 16 | 84492315 |
| 17 | 302014619 |
| 18 | 1077860479 |
| 19 | 3843695976 |
| 20 | 13690026688 |