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 | 20 |
| 3 | 165 |
| 4 | 1484 |
| 5 | 13986 |
| 6 | 135960 |
| 7 | 1352637 |
| 8 | 13707980 |
| 9 | 141061206 |
| 10 | 1470489800 |
| 11 | 15500280978 |
| 12 | 164967244792 |
| 13 | 1770548369700 |
| 14 | 19143828730800 |
| 15 | 208347968093085 |
| 16 | 2280730450967820 |
| 17 | 25096531231958670 |
| 18 | 277445318198433000 |