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 | 4 |
| 2 | 32 |
| 3 | 320 |
| 4 | 3536 |
| 5 | 41344 |
| 6 | 501264 |
| 7 | 6232736 |
| 8 | 78948912 |
| 9 | 1014329856 |
| 10 | 13178920016 |
| 11 | 172789849952 |
| 12 | 2282474558160 |
| 13 | 30340247738176 |
| 14 | 405461900524400 |
| 15 | 5443463231234592 |
| 16 | 73372619284217776 |
| 17 | 992459740253399360 |
| 18 | 13465895431077568080 |
| 19 | 183211658096891394848 |
| 20 | 2498857102607629076880 |