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 | 45 |
| 2 | 1125 |
| 3 | 20625 |
| 4 | 309375 |
| 5 | 4021875 |
| 6 | 46921875 |
| 7 | 502734375 |
| 8 | 5027343750 |
| 9 | 47480468750 |
| 10 | 427324218750 |
| 11 | 3690527343750 |
| 12 | 30754394531250 |
| 13 | 248400878906250 |
| 14 | 1951721191406250 |
| 15 | 14963195800781250 |
| 16 | 112223968505859375 |
| 17 | 825176239013671875 |
| 18 | 5959606170654296875 |
| 19 | 42344570159912109375 |