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 | 0 |
| 4 | 2 |
| 5 | 25 |
| 6 | 198 |
| 7 | 1274 |
| 8 | 7280 |
| 9 | 38556 |
| 10 | 193800 |
| 11 | 937992 |
| 12 | 4412826 |
| 13 | 20309575 |
| 14 | 91861770 |
| 15 | 409704750 |
| 16 | 1806342720 |
| 17 | 7887861960 |
| 18 | 34166674800 |
| 19 | 146977222320 |
| 20 | 628521016500 |
| 21 | 2673950235138 |
| 22 | 11324837666604 |
| 23 | 47773836727540 |
| 24 | 200828153398752 |