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 | 4 |
| 2 | 13 |
| 3 | 49 |
| 4 | 157 |
| 5 | 481 |
| 6 | 1534 |
| 7 | 4693 |
| 8 | 14170 |
| 9 | 43357 |
| 10 | 130918 |
| 11 | 393601 |
| 12 | 1188454 |
| 13 | 3573013 |
| 14 | 10726690 |
| 15 | 32248957 |
| 16 | 96815758 |
| 17 | 290516161 |
| 18 | 872169223 |
| 19 | 2617128409 |
| 20 | 7852005967 |
| 21 | 23561605318 |
| 22 | 70690403371 |
| 23 | 212076797530 |
| 24 | 636280680100 |
| 25 | 1908892327810 |
| 26 | 5726727270940 |
| 27 | 17180634420931 |