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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 40 |
| 7 | 154 |
| 8 | 660 |
| 9 | 3114 |
| 10 | 15930 |
| 11 | 87645 |
| 12 | 514851 |
| 13 | 3211220 |
| 14 | 21166029 |
| 15 | 146849903 |
| 16 | 1068808441 |
| 17 | 8136559688 |
| 18 | 64621235409 |
| 19 | 534207882566 |