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 | 4 |
| 3 | 16 |
| 4 | 42 |
| 5 | 137 |
| 6 | 443 |
| 7 | 1365 |
| 8 | 4316 |
| 9 | 13625 |
| 10 | 42785 |
| 11 | 134758 |
| 12 | 424331 |
| 13 | 1335378 |
| 14 | 4203927 |
| 15 | 13233947 |
| 16 | 41657808 |
| 17 | 131135696 |
| 18 | 412803240 |
| 19 | 1299458257 |
| 20 | 4090567673 |
| 21 | 12876698159 |
| 22 | 40534529294 |
| 23 | 127598621869 |
| 24 | 401667591501 |
| 25 | 1264408966284 |
| 26 | 3980231826575 |
| 27 | 12529367967276 |
| 28 | 39441185140197 |