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 | 0 |
| 2 | 30 |
| 3 | 5670 |
| 4 | 2543940 |
| 5 | 2147121900 |
| 6 | 3060711804150 |
| 7 | 6822508357214550 |
| 8 | 22450423357516354200 |
| 9 | 104310014134397398727400 |
| 10 | 660475190873012530467201750 |
| 11 | 5537072793132139084007288856750 |
| 12 | 60005787711473418534665255077267500 |
| 13 | 823803200874542135657355819087997282500 |