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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 38 |
| 6 | 122 |
| 7 | 372 |
| 8 | 1119 |
| 9 | 3301 |
| 10 | 9624 |
| 11 | 27756 |
| 12 | 79380 |
| 13 | 225384 |
| 14 | 636061 |
| 15 | 1785639 |
| 16 | 4990116 |
| 17 | 13889618 |
| 18 | 38524238 |
| 19 | 106514652 |
| 20 | 293668923 |
| 21 | 807608137 |
| 22 | 2215854384 |
| 23 | 6066935640 |
| 24 | 16579195560 |
| 25 | 45226399440 |
| 26 | 123173004985 |
| 27 | 334955873739 |
| 28 | 909611388732 |
| 29 | 2466965351678 |
| 30 | 6682629071522 |