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 | 1 |
| 3 | 6 |
| 4 | 13 |
| 5 | 49 |
| 6 | 132 |
| 7 | 433 |
| 8 | 1261 |
| 9 | 3942 |
| 10 | 11809 |
| 11 | 36289 |
| 12 | 109824 |
| 13 | 335425 |
| 14 | 1018849 |
| 15 | 3104934 |
| 16 | 9443629 |
| 17 | 28756657 |
| 18 | 87504516 |
| 19 | 266383153 |
| 20 | 810723277 |
| 21 | 2467770054 |
| 22 | 7510988353 |
| 23 | 22861948801 |
| 24 | 69584925696 |
| 25 | 211799836801 |
| 26 | 644660351425 |