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 | 20 |
| 2 | 160 |
| 3 | 1040 |
| 4 | 7880 |
| 5 | 60720 |
| 6 | 479296 |
| 7 | 3835544 |
| 8 | 31025864 |
| 9 | 253006376 |
| 10 | 2076361620 |
| 11 | 17126818652 |
| 12 | 141850168856 |
| 13 | 1178779027316 |
| 14 | 9822495145882 |
| 15 | 82032520847910 |
| 16 | 686360207228280 |
| 17 | 5751457669257720 |
| 18 | 48255474860875126 |
| 19 | 405286028562477798 |