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 | 20 |
| 4 | 129 |
| 5 | 1164 |
| 6 | 12265 |
| 7 | 151458 |
| 8 | 2136337 |
| 9 | 33901640 |
| 10 | 597761361 |
| 11 | 11593851510 |
| 12 | 245310524041 |
| 13 | 5622982528188 |
| 14 | 138803996674057 |
| 15 | 3671135646515834 |
| 16 | 103568483199034785 |
| 17 | 3104443346427521808 |
| 18 | 98528857134710517793 |