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 | 4095 |
| 3 | 265720 |
| 4 | 8386560 |
| 5 | 61035156 |
| 6 | 1088123400 |
| 7 | 2306881200 |
| 8 | 17175674880 |
| 9 | 47071500840 |
| 10 | 249938963820 |
| 11 | 313842837672 |
| 12 | 2228476723200 |
| 13 | 1941507093540 |
| 14 | 9446678514000 |
| 15 | 16218261652320 |
| 16 | 35175782154240 |
| 17 | 36413889826860 |
| 18 | 192757795939800 |
| 19 | 122961939948120 |
| 20 | 511874997903360 |
| 21 | 612984472464000 |