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 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 68 |
| 5 | 629 |
| 6 | 7797 |
| 7 | 117655 |
| 8 | 2097254 |
| 9 | 43046979 |
| 10 | 1000000799 |
| 11 | 25937424611 |
| 12 | 743008402000 |
| 13 | 23298085122493 |
| 14 | 793714773374529 |
| 15 | 29192926027528343 |
| 16 | 1152921504613147242 |
| 17 | 48661191875666868497 |
| 18 | 2185911559739107208115 |
| 19 | 104127350297911241532859 |
| 20 | 5242880000000008181608132 |