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 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 241 |
| 5 | 3951 |
| 6 | 85499 |
| 7 | 2325205 |
| 8 | 76860673 |
| 9 | 3014656183 |
| 10 | 137784836475 |
| 11 | 7235668490589 |
| 12 | 431692029451009 |
| 13 | 28991550501283359 |
| 14 | 2174713803535479419 |
| 15 | 181001542259074421413 |
| 16 | 16618721538838243841185 |
| 17 | 1674634828088234390862727 |
| 18 | 184352162064651888588105243 |