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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 13 |
| 3 | 55 |
| 4 | 217 |
| 5 | 811 |
| 6 | 2917 |
| 7 | 10207 |
| 8 | 34993 |
| 9 | 118099 |
| 10 | 393661 |
| 11 | 1299079 |
| 12 | 4251529 |
| 13 | 13817467 |
| 14 | 44641045 |
| 15 | 143489071 |
| 16 | 459165025 |
| 17 | 1463588515 |
| 18 | 4649045869 |
| 19 | 14721978583 |
| 20 | 46490458681 |
| 21 | 146444944843 |
| 22 | 460255540933 |
| 23 | 1443528742015 |
| 24 | 4518872583697 |
| 25 | 14121476824051 |
| 26 | 44059007691037 |
| 27 | 137260754729767 |