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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 6 |
| 8 | 6 |
| 9 | 18 |
| 10 | 18 |
| 11 | 18 |
| 12 | 54 |
| 13 | 54 |
| 14 | 378 |
| 15 | 1134 |
| 16 | 1134 |
| 17 | 9072 |
| 18 | 81648 |
| 19 | 81648 |
| 20 | 81648 |
| 21 | 1714608 |
| 22 | 18860688 |
| 23 | 18860688 |
| 24 | 56582064 |
| 25 | 56582064 |
| 26 | 735566832 |
| 27 | 19860304464 |
| 28 | 139022131248 |
| 29 | 139022131248 |
| 30 | 417066393744 |
| 31 | 2085331968720 |
| 32 | 2085331968720 |
| 33 | 68815954967760 |