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) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 31 |
| 6 | 80 |
| 7 | 229 |
| 8 | 681 |
| 9 | 1969 |
| 10 | 5973 |
| 11 | 18031 |
| 12 | 54874 |
| 13 | 167752 |
| 14 | 513625 |
| 15 | 1575095 |
| 16 | 4835994 |
| 17 | 14859480 |
| 18 | 45674676 |
| 19 | 140452387 |
| 20 | 431987865 |
| 21 | 1328865560 |
| 22 | 4088283165 |
| 23 | 12578581331 |
| 24 | 38703117525 |
| 25 | 119090222855 |
| 26 | 366452309799 |
| 27 | 1127630050984 |