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 | 1 |
| 1 | 7 |
| 2 | 42 |
| 3 | 252 |
| 4 | 1512 |
| 5 | 9051 |
| 6 | 54180 |
| 7 | 324345 |
| 8 | 1941660 |
| 9 | 11623500 |
| 10 | 69582660 |
| 11 | 416548125 |
| 12 | 2493614550 |
| 13 | 14927719275 |
| 14 | 89362970550 |
| 15 | 534960522600 |
| 16 | 3202475913000 |
| 17 | 19171231408875 |
| 18 | 114766238286000 |
| 19 | 687034086094125 |
| 20 | 4112845750671000 |