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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 708 |
| 7 | 4914 |
| 8 | 38976 |
| 9 | 347795 |
| 10 | 3448312 |
| 11 | 37608186 |
| 12 | 447452544 |
| 13 | 5767315785 |
| 14 | 80054392880 |
| 15 | 1190583423414 |
| 16 | 18887010379776 |
| 17 | 318343175603145 |
| 18 | 5681348801115680 |
| 19 | 107025793890636390 |
| 20 | 2122275973981599744 |
| 21 | 44188021441868910375 |
| 22 | 963852638874607648320 |