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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 18 |
| 4 | 92 |
| 5 | 528 |
| 6 | 3356 |
| 7 | 23344 |
| 8 | 175984 |
| 9 | 1426520 |
| 10 | 12352600 |
| 11 | 113645488 |
| 12 | 1105760224 |
| 13 | 11333738336 |
| 14 | 121957021744 |
| 15 | 1373618201360 |
| 16 | 16151326356192 |
| 17 | 197796234588800 |
| 18 | 2517603785738752 |
| 19 | 33242912468993312 |
| 20 | 454583512625280256 |
| 21 | 6427749935432143072 |
| 22 | 93847133530055987840 |