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 | 15 |
| 2 | 135 |
| 3 | 950 |
| 4 | 5670 |
| 5 | 30003 |
| 6 | 144680 |
| 7 | 647055 |
| 8 | 2717760 |
| 9 | 10820640 |
| 10 | 41128374 |
| 11 | 150073470 |
| 12 | 528074655 |
| 13 | 1798537380 |
| 14 | 5947216050 |
| 15 | 19142919543 |
| 16 | 60113026305 |
| 17 | 184513760775 |
| 18 | 554517086825 |
| 19 | 1634047143090 |
| 20 | 4727605374594 |
| 21 | 13444544485435 |
| 22 | 37620762642885 |
| 23 | 103678546403985 |
| 24 | 281639925782930 |