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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 15 |
| 4 | 150 |
| 5 | 1250 |
| 6 | 9375 |
| 7 | 65625 |
| 8 | 437500 |
| 9 | 2812500 |
| 10 | 17578125 |
| 11 | 107421875 |
| 12 | 644531250 |
| 13 | 3808593750 |
| 14 | 22216796875 |
| 15 | 128173828125 |
| 16 | 732421875000 |
| 17 | 4150390625000 |
| 18 | 23345947265625 |
| 19 | 130462646484375 |
| 20 | 724792480468750 |