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 | 180 |
| 3 | 3900 |
| 4 | 29400 |
| 5 | 442860 |
| 6 | 1206660 |
| 7 | 6034320 |
| 8 | 11761380 |
| 9 | 37008840 |
| 10 | 148705620 |
| 11 | 221875680 |
| 12 | 641431260 |
| 13 | 1187525640 |
| 14 | 1580340300 |
| 15 | 2694803280 |
| 16 | 5541089580 |
| 17 | 10545132540 |
| 18 | 12880092660 |
| 19 | 22614594420 |
| 20 | 32025069720 |
| 21 | 37833555240 |