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 | 4 |
| 2 | 12 |
| 3 | 30 |
| 4 | 72 |
| 5 | 166 |
| 6 | 376 |
| 7 | 837 |
| 8 | 1844 |
| 9 | 4025 |
| 10 | 8723 |
| 11 | 18789 |
| 12 | 40263 |
| 13 | 85892 |
| 14 | 182515 |
| 15 | 386488 |
| 16 | 815890 |
| 17 | 1717604 |
| 18 | 3606854 |
| 19 | 7556995 |
| 20 | 15800562 |
| 21 | 32974263 |
| 22 | 68694801 |
| 23 | 142882147 |
| 24 | 296749381 |
| 25 | 615468930 |
| 26 | 1274878193 |
| 27 | 2637637046 |
| 28 | 5451035408 |
| 29 | 11253593442 |
| 30 | 23210232132 |
| 31 | 47826554753 |