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 | 12 |
| 2 | 972 |
| 3 | 19640 |
| 4 | 260019 |
| 5 | 2365772 |
| 6 | 16266830 |
| 7 | 89700624 |
| 8 | 413977192 |
| 9 | 1650607040 |
| 10 | 5826331440 |
| 11 | 18558391936 |
| 12 | 54055214144 |
| 13 | 145576033920 |
| 14 | 365883104080 |
| 15 | 865023114560 |
| 16 | 1936764883296 |
| 17 | 4130528893504 |
| 18 | 8433028861040 |