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 | 3113 |
| 10 | 15893 |
| 11 | 86857 |
| 12 | 502092 |
| 13 | 3036032 |
| 14 | 19006591 |
| 15 | 122119857 |
| 16 | 799665333 |
| 17 | 5308126648 |
| 18 | 35576413852 |
| 19 | 240063646519 |
| 20 | 1627605038848 |