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) |
|---|---|
| 3 | 1 |
| 4 | 3 |
| 5 | 11 |
| 6 | 37 |
| 7 | 126 |
| 8 | 430 |
| 9 | 1454 |
| 10 | 4976 |
| 11 | 16880 |
| 12 | 57824 |
| 13 | 197010 |
| 14 | 675428 |
| 15 | 2310268 |
| 16 | 7927778 |
| 17 | 27205180 |
| 18 | 93448486 |
| 19 | 321537086 |
| 20 | 1105589516 |
| 21 | 3812424912 |
| 22 | 13121988240 |
| 23 | 45330375774 |
| 24 | 156172996170 |
| 25 | 540314673678 |
| 26 | 1863197292582 |
| 27 | 6454265995454 |
| 28 | 22275589419432 |
| 29 | 77246945788890 |
| 30 | 266813803179348 |