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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 21 |
| 5 | 53 |
| 6 | 133 |
| 7 | 309 |
| 8 | 706 |
| 9 | 1572 |
| 10 | 3534 |
| 11 | 7752 |
| 12 | 16991 |
| 13 | 36807 |
| 14 | 79385 |
| 15 | 170528 |
| 16 | 364563 |
| 17 | 776739 |
| 18 | 1649071 |
| 19 | 3490698 |
| 20 | 7366917 |
| 21 | 15512544 |
| 22 | 32583646 |
| 23 | 68306009 |
| 24 | 142902505 |
| 25 | 298446956 |
| 26 | 622232624 |
| 27 | 1295316994 |
| 28 | 2692580198 |
| 29 | 5589582431 |
| 30 | 11588900240 |
| 31 | 23999045850 |