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 | 9 |
| 4 | 29 |
| 5 | 94 |
| 6 | 310 |
| 7 | 1026 |
| 8 | 3411 |
| 9 | 11360 |
| 10 | 37886 |
| 11 | 126442 |
| 12 | 422203 |
| 13 | 1410189 |
| 14 | 4711039 |
| 15 | 15740098 |
| 16 | 52593430 |
| 17 | 175742438 |
| 18 | 587266782 |
| 19 | 1962469721 |
| 20 | 6558071499 |
| 21 | 21915580437 |
| 22 | 73237274083 |
| 23 | 244744474601 |
| 24 | 817889464220 |
| 25 | 2733235019732 |
| 26 | 9133973730633 |
| 27 | 30524096110942 |
| 28 | 102006076541264 |