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 | 0 |
| 3 | 1 |
| 4 | 0 |
| 5 | 5 |
| 6 | 4 |
| 7 | 23 |
| 8 | 36 |
| 9 | 123 |
| 10 | 252 |
| 11 | 720 |
| 12 | 1664 |
| 13 | 4427 |
| 14 | 10804 |
| 15 | 27971 |
| 16 | 69972 |
| 17 | 179469 |
| 18 | 454300 |
| 19 | 1162529 |
| 20 | 2961056 |
| 21 | 7579620 |
| 22 | 19376728 |
| 23 | 49659406 |
| 24 | 127263208 |
| 25 | 326610827 |
| 26 | 838550920 |
| 27 | 2154985059 |
| 28 | 5540935616 |
| 29 | 14257159799 |
| 30 | 36703613556 |
| 31 | 94544579575 |