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 | 9 |
| 2 | 71 |
| 3 | 519 |
| 4 | 3606 |
| 5 | 24150 |
| 6 | 157250 |
| 7 | 1001250 |
| 8 | 6259375 |
| 9 | 38534375 |
| 10 | 234140625 |
| 11 | 1406640625 |
| 12 | 8367187500 |
| 13 | 49335937500 |
| 14 | 288632812500 |
| 15 | 1676757812500 |
| 16 | 9678955078125 |
| 17 | 55548095703125 |
| 18 | 317108154296875 |
| 19 | 1801483154296875 |
| 20 | 10188293457031250 |
| 21 | 57380676269531250 |
| 22 | 321922302246093750 |