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 | 6 |
| 3 | 60 |
| 4 | 140 |
| 5 | 630 |
| 6 | 31416 |
| 7 | 34580 |
| 8 | 91080 |
| 9 | 1093950 |
| 10 | 58549260 |
| 11 | 6702696 |
| 12 | 61910940 |
| 13 | 2379795600 |
| 14 | 1197892080 |
| 15 | 21742542360 |
| 16 | 21741799002768 |
| 17 | 143830236550 |
| 18 | 2559047531040 |
| 19 | 38886283310 |
| 20 | 333903908520 |
| 21 | 24063048428483064 |