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 | 7 |
| 2 | 56 |
| 3 | 470 |
| 4 | 4048 |
| 5 | 35443 |
| 6 | 313912 |
| 7 | 2804012 |
| 8 | 25211936 |
| 9 | 227881004 |
| 10 | 2068564064 |
| 11 | 18844224462 |
| 12 | 172186125456 |
| 13 | 1577401391626 |
| 14 | 14483100716176 |
| 15 | 133240186921816 |
| 16 | 1227901991526976 |
| 17 | 11333497984085620 |
| 18 | 104752914242685856 |
| 19 | 969417048912326008 |
| 20 | 8981452266787224128 |