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 | 2 |
| 2 | 16 |
| 3 | 144 |
| 4 | 1280 |
| 5 | 12416 |
| 6 | 156288 |
| 7 | 2445952 |
| 8 | 39005696 |
| 9 | 569584128 |
| 10 | 7551139840 |
| 11 | 94905663488 |
| 12 | 1200235880448 |
| 13 | 15657039026176 |
| 14 | 204235121909760 |
| 15 | 2589347043356672 |
| 16 | 34080849916796928 |
| 17 | 554466780012625920 |
| 18 | 11679936697324273664 |
| 19 | 269604415927633805312 |
| 20 | 6025264829519275556864 |