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 | 2 |
| 3 | 24 |
| 4 | 384 |
| 5 | 8160 |
| 6 | 218880 |
| 7 | 7116480 |
| 8 | 272240640 |
| 9 | 11985200640 |
| 10 | 596981145600 |
| 11 | 33195609216000 |
| 12 | 2038500521164800 |
| 13 | 137021183973273600 |
| 14 | 10006412139653529600 |
| 15 | 788930789450259456000 |
| 16 | 66790064645111808000000 |
| 17 | 6042970648669883056128000 |
| 18 | 581917311773908793819136000 |
| 19 | 59423732260666221275283456000 |