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 | 16 |
| 4 | 88 |
| 5 | 568 |
| 6 | 4288 |
| 7 | 36832 |
| 8 | 354688 |
| 9 | 3781504 |
| 10 | 44199424 |
| 11 | 561823744 |
| 12 | 7714272256 |
| 13 | 113769309184 |
| 14 | 1793341407232 |
| 15 | 30085661765632 |
| 16 | 535170830467072 |
| 17 | 10060645294440448 |
| 18 | 199287423535808512 |
| 19 | 4148644277780217856 |
| 20 | 90545807649965080576 |
| 21 | 2067407731760475406336 |
| 22 | 49285894020028992323584 |