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 | 4 |
| 4 | 14 |
| 5 | 44 |
| 6 | 135 |
| 7 | 408 |
| 8 | 1228 |
| 9 | 3688 |
| 10 | 11069 |
| 11 | 33212 |
| 12 | 99642 |
| 13 | 298932 |
| 14 | 896803 |
| 15 | 2690416 |
| 16 | 8071256 |
| 17 | 24213776 |
| 18 | 72641337 |
| 19 | 217924020 |
| 20 | 653772070 |
| 21 | 1961316220 |
| 22 | 5883948671 |
| 23 | 17651846024 |
| 24 | 52955538084 |
| 25 | 158866614264 |
| 26 | 476599842805 |