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 | 1 |
| 3 | 8 |
| 4 | 20 |
| 5 | 104 |
| 6 | 378 |
| 7 | 1670 |
| 8 | 6706 |
| 9 | 28417 |
| 10 | 117204 |
| 11 | 490865 |
| 12 | 2039569 |
| 13 | 8512474 |
| 14 | 35444636 |
| 15 | 147780722 |
| 16 | 615715196 |
| 17 | 2566325356 |
| 18 | 10694300534 |
| 19 | 44570089963 |
| 20 | 185740837148 |
| 21 | 774080813649 |
| 22 | 3225945847829 |
| 23 | 13444117980220 |
| 24 | 56028001091944 |
| 25 | 233495908297044 |
| 26 | 973089296878098 |
| 27 | 4055332929187618 |
| 28 | 16900521902518438 |