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 | 5 |
| 5 | 15 |
| 6 | 54 |
| 7 | 212 |
| 8 | 908 |
| 9 | 4011 |
| 10 | 18260 |
| 11 | 84320 |
| 12 | 394462 |
| 13 | 1860872 |
| 14 | 8843896 |
| 15 | 42275308 |
| 16 | 203113670 |
| 17 | 980101070 |
| 18 | 4747504560 |
| 19 | 23074132601 |