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 | 15 |
| 6 | 90 |
| 7 | 630 |
| 8 | 720 |
| 9 | 45360 |
| 10 | 64800 |
| 11 | 4989600 |
| 12 | 59875200 |
| 13 | 778377600 |
| 14 | 1556755200 |
| 15 | 163459296000 |
| 16 | 373621248000 |
| 17 | 44460928512000 |
| 18 | 800296713216000 |
| 19 | 15205637551104000 |
| 20 | 3949516247040000 |
| 21 | 6386367771463680000 |
| 22 | 20071441567457280000 |
| 23 | 3231502092360622080000 |
| 24 | 5965850016665763840000 |
| 25 | 1938901255416373248000000 |
| 26 | 7201633234403672064000000 |