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 | 2 |
| 2 | 3 |
| 3 | 7 |
| 4 | 31 |
| 5 | 181 |
| 6 | 1621 |
| 7 | 19441 |
| 8 | 311041 |
| 9 | 6842881 |
| 10 | 171072001 |
| 11 | 4961088001 |
| 12 | 153793728001 |
| 13 | 5382780480001 |
| 14 | 252990682560001 |
| 15 | 14420468905920001 |
| 16 | 879648603261120001 |
| 17 | 58056807815233920001 |
| 18 | 4586487817403479680001 |
| 19 | 371505513209681854080001 |
| 20 | 40122595426645640240640001 |