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 | 2 |
| 2 | 12 |
| 3 | 48 |
| 4 | 167 |
| 5 | 541 |
| 6 | 1692 |
| 7 | 5187 |
| 8 | 15700 |
| 9 | 47030 |
| 10 | 139986 |
| 11 | 415385 |
| 12 | 1230417 |
| 13 | 3638657 |
| 14 | 10744058 |
| 15 | 31705658 |
| 16 | 93563017 |
| 17 | 276079102 |
| 18 | 814408697 |
| 19 | 2402076923 |
| 20 | 7085491321 |
| 21 | 20902994644 |
| 22 | 61668276920 |
| 23 | 181926014930 |
| 24 | 536710980085 |
| 25 | 1583529043750 |
| 26 | 4672393755494 |
| 27 | 13786612213841 |