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 | 720 |
| 2 | 665280 |
| 3 | 13366080 |
| 4 | 96909120 |
| 5 | 427518000 |
| 6 | 1402410240 |
| 7 | 3776965920 |
| 8 | 8835488640 |
| 9 | 18595558800 |
| 10 | 36045979200 |
| 11 | 65418312960 |
| 12 | 112492013760 |
| 13 | 184933148400 |
| 14 | 292666711680 |
| 15 | 448282533600 |
| 16 | 667474778880 |
| 17 | 969515038800 |
| 18 | 1377759015360 |
| 19 | 1920186797760 |
| 20 | 2629976731200 |