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 | 26 |
| 3 | 154 |
| 4 | 926 |
| 5 | 5554 |
| 6 | 33326 |
| 7 | 199954 |
| 8 | 1199726 |
| 9 | 7198354 |
| 10 | 43190126 |
| 11 | 259140754 |
| 12 | 1554844526 |
| 13 | 9329067154 |
| 14 | 55974402926 |
| 15 | 335846417554 |
| 16 | 2015078505326 |
| 17 | 12090471031954 |
| 18 | 72542826191726 |
| 19 | 435256957150354 |
| 20 | 2611541742902126 |