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 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 30 |
| 7 | 70 |
| 8 | 140 |
| 9 | 1260 |
| 10 | 6300 |
| 11 | 23100 |
| 12 | 138600 |
| 13 | 600600 |
| 14 | 2102100 |
| 15 | 10510500 |
| 16 | 42042000 |
| 17 | 142942800 |
| 18 | 1286485200 |
| 19 | 8147739600 |
| 20 | 40738698000 |
| 21 | 285170886000 |
| 22 | 1568439873000 |
| 23 | 7214823415800 |
| 24 | 43288940494800 |
| 25 | 216444702474000 |