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 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 8 |
| 7 | 20 |
| 8 | 50 |
| 9 | 125 |
| 10 | 375 |
| 11 | 1125 |
| 12 | 3375 |
| 13 | 11700 |
| 14 | 40560 |
| 15 | 140608 |
| 16 | 548912 |
| 17 | 2142868 |
| 18 | 8365427 |
| 19 | 36140293 |
| 20 | 156133187 |
| 21 | 674526133 |
| 22 | 3184194060 |
| 23 | 15031429200 |
| 24 | 70957944000 |
| 25 | 362451121200 |
| 26 | 1851389821260 |
| 27 | 9456845543523 |
| 28 | 51863510753775 |
| 29 | 284431392616875 |