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 | 55 |
| 3 | 440 |
| 4 | 5170 |
| 5 | 56408 |
| 6 | 620950 |
| 7 | 6830120 |
| 8 | 75131485 |
| 9 | 826446280 |
| 10 | 9090909091 |
| 11 | 100000000000 |
| 12 | 1100000000000 |
| 13 | 12100000000000 |
| 14 | 133100000000000 |
| 15 | 1464100000000000 |
| 16 | 16105100000000000 |
| 17 | 177156100000000000 |
| 18 | 1948717100000000000 |
| 19 | 21435888100000000000 |
| 20 | 235794769100000000000 |