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 | 9 |
| 2 | 36 |
| 3 | 240 |
| 4 | 1620 |
| 5 | 11808 |
| 6 | 88440 |
| 7 | 683280 |
| 8 | 5380020 |
| 9 | 43046640 |
| 10 | 348672528 |
| 11 | 2852823600 |
| 12 | 23535749880 |
| 13 | 195528140640 |
| 14 | 1634056262280 |
| 15 | 13726075468992 |
| 16 | 115813759112820 |
| 17 | 981010688215680 |
| 18 | 8338590828280440 |
| 19 | 71097458824894320 |