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) |
|---|---|
| 2 | 20 |
| 3 | 390 |
| 4 | 2930 |
| 5 | 23580 |
| 6 | 145210 |
| 7 | 1045940 |
| 8 | 6228730 |
| 9 | 43322370 |
| 10 | 260600210 |
| 11 | 1776654220 |
| 12 | 10913989610 |
| 13 | 73525916750 |
| 14 | 461264468640 |
| 15 | 3088176680560 |
| 16 | 19722405442490 |
| 17 | 131703577902460 |
| 18 | 853035459491710 |
| 19 | 5693694272274220 |
| 20 | 37271158654667390 |
| 21 | 248902943147007900 |