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 | 2 |
| 1 | 6 |
| 2 | 26 |
| 3 | 126 |
| 4 | 626 |
| 5 | 3126 |
| 6 | 15626 |
| 7 | 78126 |
| 8 | 390626 |
| 9 | 1953126 |
| 10 | 9765626 |
| 11 | 48828126 |
| 12 | 244140626 |
| 13 | 1220703126 |
| 14 | 6103515626 |
| 15 | 30517578126 |
| 16 | 152587890626 |
| 17 | 762939453126 |
| 18 | 3814697265626 |
| 19 | 19073486328126 |
| 20 | 95367431640626 |
| 21 | 476837158203126 |