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) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 20 |
| 4 | 70 |
| 5 | 245 |
| 6 | 860 |
| 7 | 3015 |
| 8 | 10570 |
| 9 | 37060 |
| 10 | 129935 |
| 11 | 455560 |
| 12 | 1597225 |
| 13 | 5599980 |
| 14 | 19633910 |
| 15 | 68837825 |
| 16 | 241350100 |
| 17 | 846189875 |
| 18 | 2966799290 |
| 19 | 10401800220 |
| 20 | 36469419475 |
| 21 | 127864266640 |
| 22 | 448300820765 |
| 23 | 1571773187140 |
| 24 | 5510743762630 |