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 | 45 |
| 4 | 549 |
| 5 | 3755 |
| 6 | 18120 |
| 7 | 69006 |
| 8 | 220710 |
| 9 | 616554 |
| 10 | 1545435 |
| 11 | 3544915 |
| 12 | 7552611 |
| 13 | 15119325 |
| 14 | 28699034 |
| 15 | 52032540 |
| 16 | 90643260 |
| 17 | 152465316 |
| 18 | 248625765 |
| 19 | 394404489 |
| 20 | 610396945 |
| 21 | 923906655 |
| 22 | 1370595996 |
| 23 | 1996425530 |
| 24 | 2859913794 |
| 25 | 4034751150 |
| 26 | 5612802975 |
| 27 | 7707539151 |
| 28 | 10457928495 |