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) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 17 |
| 7 | 66 |
| 8 | 254 |
| 9 | 956 |
| 10 | 3584 |
| 11 | 13256 |
| 12 | 49052 |
| 13 | 179552 |
| 14 | 658560 |
| 15 | 2394504 |
| 16 | 8724464 |
| 17 | 31575096 |
| 18 | 114451388 |
| 19 | 412811544 |
| 20 | 1490190544 |
| 21 | 5360943684 |
| 22 | 19288139802 |
| 23 | 69245171564 |
| 24 | 248463024330 |
| 25 | 890477645192 |
| 26 | 3188033497580 |
| 27 | 11409453277272 |
| 28 | 40771092374710 |
| 29 | 145735210316376 |
| 30 | 519955750491512 |