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 | 0 |
| 1 | 1 |
| 2 | 16 |
| 3 | 193 |
| 4 | 2080 |
| 5 | 21121 |
| 6 | 206896 |
| 7 | 1979713 |
| 8 | 18640960 |
| 9 | 173533441 |
| 10 | 1602154576 |
| 11 | 14701866433 |
| 12 | 134294124640 |
| 13 | 1222488408961 |
| 14 | 11099284691056 |
| 15 | 100571785292353 |
| 16 | 909893629141120 |
| 17 | 8222275592839681 |
| 18 | 74233110849544336 |
| 19 | 669726411243809473 |
| 20 | 6038936596379658400 |
| 21 | 54430221633714537601 |