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 | 4 |
| 2 | 8 |
| 3 | 18 |
| 4 | 126 |
| 5 | 380 |
| 6 | 4112 |
| 7 | 14310 |
| 8 | 184410 |
| 9 | 9272780 |
| 10 | 34669602 |
| 11 | 1857545300 |
| 12 | 26818405352 |
| 13 | 102282248574 |
| 14 | 1497215711538 |
| 15 | 84973644983780 |
| 16 | 4885261149611790 |
| 17 | 18900353608280300 |
| 18 | 1101298162244236182 |
| 19 | 16628051030379615882 |