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 | 15 |
| 2 | 186 |
| 3 | 1680 |
| 4 | 15876 |
| 5 | 123690 |
| 6 | 1541568 |
| 7 | 8992680 |
| 8 | 111757968 |
| 9 | 967814400 |
| 10 | 9366647892 |
| 11 | 62424587520 |
| 12 | 852903426816 |
| 13 | 4766016364260 |
| 14 | 55176998178240 |
| 15 | 550081165885440 |
| 16 | 4829754617483040 |
| 17 | 31725040326819840 |
| 18 | 471309320999516160 |
| 19 | 2535353780263288800 |
| 20 | 33995669076586206864 |