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 | 13 |
| 3 | 147 |
| 4 | 1625 |
| 5 | 17891 |
| 6 | 196833 |
| 7 | 2165227 |
| 8 | 23817625 |
| 9 | 261994131 |
| 10 | 2881935943 |
| 11 | 31701296375 |
| 12 | 348714262017 |
| 13 | 3835856884757 |
| 14 | 42194425724149 |
| 15 | 464138682802857 |
| 16 | 5105525508895321 |
| 17 | 56160780576260645 |
| 18 | 617768586100819485 |
| 19 | 6795454444489330049 |
| 20 | 74749998860563784655 |