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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 4 |
| 6 | 14 |
| 7 | 34 |
| 8 | 98 |
| 9 | 270 |
| 10 | 768 |
| 11 | 2192 |
| 12 | 6360 |
| 13 | 18576 |
| 14 | 54780 |
| 15 | 162658 |
| 16 | 486154 |
| 17 | 1461174 |
| 18 | 4413988 |
| 19 | 13393816 |
| 20 | 40807290 |
| 21 | 124783604 |
| 22 | 382842018 |
| 23 | 1178140170 |
| 24 | 3635626680 |
| 25 | 11247841040 |
| 26 | 34880346840 |
| 27 | 108402132234 |
| 28 | 337576497920 |
| 29 | 1053229357732 |
| 30 | 3291813720292 |
| 31 | 10305275270364 |