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 | 5 |
| 2 | 20 |
| 3 | 135 |
| 4 | 1040 |
| 5 | 7151 |
| 6 | 45360 |
| 7 | 277535 |
| 8 | 1675520 |
| 9 | 10071135 |
| 10 | 60456176 |
| 11 | 362782415 |
| 12 | 2176761600 |
| 13 | 13060665455 |
| 14 | 78364125680 |
| 15 | 470184933951 |
| 16 | 2821109841920 |
| 17 | 16926659361215 |
| 18 | 101559956563440 |
| 19 | 609359739880175 |