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 | 1 |
| 1 | 56 |
| 2 | 1540 |
| 3 | 27720 |
| 4 | 367290 |
| 5 | 3819816 |
| 6 | 32468436 |
| 7 | 231917400 |
| 8 | 1420494075 |
| 9 | 7575968400 |
| 10 | 35607051480 |
| 11 | 148902215280 |
| 12 | 558383307300 |
| 13 | 1889912732400 |
| 14 | 5804731963800 |
| 15 | 16253249498640 |
| 16 | 41648951840265 |
| 17 | 97997533741800 |
| 18 | 212327989773900 |
| 19 | 424655979547800 |
| 20 | 785613562163430 |