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 | 6 |
| 4 | 21 |
| 5 | 57 |
| 6 | 138 |
| 7 | 330 |
| 8 | 827 |
| 9 | 2175 |
| 10 | 5826 |
| 11 | 15519 |
| 12 | 40836 |
| 13 | 106584 |
| 14 | 277696 |
| 15 | 724968 |
| 16 | 1897380 |
| 17 | 4972113 |
| 18 | 13029534 |
| 19 | 34125561 |
| 20 | 89336141 |
| 21 | 233831262 |
| 22 | 612074526 |
| 23 | 1602358863 |
| 24 | 4195173507 |
| 25 | 10983645498 |
| 26 | 28756340047 |
| 27 | 75285234408 |
| 28 | 197097337248 |
| 29 | 516002648064 |