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 | 2 |
| 2 | 5 |
| 3 | 24 |
| 4 | 133 |
| 5 | 736 |
| 6 | 4135 |
| 7 | 23452 |
| 8 | 134043 |
| 9 | 770864 |
| 10 | 4455462 |
| 11 | 25859380 |
| 12 | 150615223 |
| 13 | 879876040 |
| 14 | 5153445895 |
| 15 | 30251941860 |
| 16 | 177938418225 |
| 17 | 1048452751872 |
| 18 | 6187400646130 |
| 19 | 36566048896896 |
| 20 | 216370786646054 |