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 | 0 |
| 1 | 1 |
| 2 | 1040 |
| 3 | 59130 |
| 4 | 1065216 |
| 5 | 9766250 |
| 6 | 61495200 |
| 7 | 282477650 |
| 8 | 1090785280 |
| 9 | 3491573931 |
| 10 | 10156900000 |
| 11 | 25937439242 |
| 12 | 62986222080 |
| 13 | 137858520410 |
| 14 | 293776756000 |
| 15 | 577478362500 |
| 16 | 1116964192256 |
| 17 | 2015993983970 |
| 18 | 3631236888240 |
| 19 | 6131066388122 |
| 20 | 10403165760000 |
| 21 | 16702903444500 |
| 22 | 26974936811680 |