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 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 32 |
| 6 | 90 |
| 7 | 252 |
| 8 | 714 |
| 9 | 2032 |
| 10 | 5814 |
| 11 | 16700 |
| 12 | 48136 |
| 13 | 139152 |
| 14 | 403286 |
| 15 | 1171380 |
| 16 | 3409020 |
| 17 | 9938304 |
| 18 | 29017878 |
| 19 | 84844044 |
| 20 | 248382516 |
| 21 | 727971360 |
| 22 | 2135784798 |
| 23 | 6272092596 |
| 24 | 18435108258 |
| 25 | 54228499920 |
| 26 | 159636389850 |
| 27 | 470256930052 |
| 28 | 1386170197704 |