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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 24 |
| 6 | 66 |
| 7 | 180 |
| 8 | 522 |
| 9 | 1532 |
| 10 | 4624 |
| 11 | 14136 |
| 12 | 43930 |
| 13 | 137908 |
| 14 | 437502 |
| 15 | 1399068 |
| 16 | 4507352 |
| 17 | 14611576 |
| 18 | 47633486 |
| 19 | 156047204 |
| 20 | 513477502 |
| 21 | 1696305728 |
| 22 | 5623993944 |
| 23 | 18706733128 |
| 24 | 62408176762 |
| 25 | 208769240140 |
| 26 | 700129713630 |
| 27 | 2353386723912 |