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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 4 |
| 6 | 8 |
| 7 | 18 |
| 8 | 44 |
| 9 | 104 |
| 10 | 242 |
| 11 | 564 |
| 12 | 1320 |
| 13 | 3090 |
| 14 | 7228 |
| 15 | 16904 |
| 16 | 39538 |
| 17 | 92484 |
| 18 | 216328 |
| 19 | 506002 |
| 20 | 1183564 |
| 21 | 2768424 |
| 22 | 6475506 |
| 23 | 15146580 |
| 24 | 35428712 |
| 25 | 82869778 |
| 26 | 193837148 |
| 27 | 453396168 |
| 28 | 1060519538 |
| 29 | 2480615780 |
| 30 | 5802302024 |
| 31 | 13571915922 |
| 32 | 31745486700 |
| 33 | 74254506984 |