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 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 16 |
| 6 | 76 |
| 7 | 1016 |
| 8 | 10284 |
| 9 | 157340 |
| 10 | 2411756 |
| 11 | 44953712 |
| 12 | 899824256 |
| 13 | 20283419872 |
| 14 | 495216726096 |
| 15 | 13202082981712 |
| 16 | 378896535199888 |
| 17 | 11690436112988224 |
| 18 | 385173160930360192 |
| 19 | 13509981115738946816 |
| 20 | 502374681770910293568 |
| 21 | 19746124320077115154112 |
| 22 | 817908018939079281840320 |