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 | 2 |
| 2 | 20 |
| 3 | 110 |
| 4 | 2600 |
| 5 | 16150 |
| 6 | 208012 |
| 7 | 1376550 |
| 8 | 74437200 |
| 9 | 511755750 |
| 10 | 7134913500 |
| 11 | 50315410002 |
| 12 | 1433226830360 |
| 13 | 10292051290430 |
| 14 | 148889972762300 |
| 15 | 1083802983548950 |
| 16 | 126935005433253024 |
| 17 | 933787075442258310 |
| 18 | 13799767368300523260 |