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 | 2 |
| 2 | 13 |
| 3 | 81 |
| 4 | 504 |
| 5 | 3136 |
| 6 | 19513 |
| 7 | 121415 |
| 8 | 755476 |
| 9 | 4700770 |
| 10 | 29249425 |
| 11 | 181997601 |
| 12 | 1132436852 |
| 13 | 7046319384 |
| 14 | 43844049029 |
| 15 | 272809183135 |
| 16 | 1697490356184 |
| 17 | 10562230626642 |
| 18 | 65720971788709 |
| 19 | 408933139743937 |
| 20 | 2544489349890656 |