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 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 10 |
| 5 | 40 |
| 6 | 212 |
| 7 | 1086 |
| 8 | 6550 |
| 9 | 43978 |
| 10 | 326462 |
| 11 | 2704096 |
| 12 | 24307174 |
| 13 | 240782702 |
| 14 | 2546166908 |
| 15 | 29250772016 |
| 16 | 355838290758 |
| 17 | 4658858733922 |
| 18 | 64127558524832 |
| 19 | 940320570514884 |