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 | 6 |
| 3 | 24 |
| 4 | 84 |
| 5 | 275 |
| 6 | 864 |
| 7 | 2639 |
| 8 | 7896 |
| 9 | 23256 |
| 10 | 67650 |
| 11 | 194821 |
| 12 | 556416 |
| 13 | 1578109 |
| 14 | 4449354 |
| 15 | 12480600 |
| 16 | 34852944 |
| 17 | 96949079 |
| 18 | 268746336 |
| 19 | 742675211 |
| 20 | 2046683100 |
| 21 | 5626200216 |
| 22 | 15430992126 |
| 23 | 42235173769 |
| 24 | 115380647424 |
| 25 | 314656725625 |
| 26 | 856733282574 |
| 27 | 2329224424344 |
| 28 | 6323840144076 |