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 | 2 |
| 1 | 30 |
| 2 | 156 |
| 3 | 2088 |
| 4 | 24480 |
| 5 | 314158 |
| 6 | 1570792 |
| 7 | 15697800 |
| 8 | 142466688 |
| 9 | 2074821104 |
| 10 | 20847434400 |
| 11 | 157079632678 |
| 12 | 2899112679360 |
| 13 | 31222486232352 |
| 14 | 306850390136136 |
| 15 | 2887898768697600 |
| 16 | 13458068181774720 |
| 17 | 314159264051394168 |
| 18 | 951904100434798080 |
| 19 | 15678880610226432000 |