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 | 0 |
| 2 | 6 |
| 3 | 18 |
| 4 | 80 |
| 5 | 296 |
| 6 | 1154 |
| 7 | 4376 |
| 8 | 16547 |
| 9 | 62222 |
| 10 | 233880 |
| 11 | 878268 |
| 12 | 3297368 |
| 13 | 12383528 |
| 14 | 46541138 |
| 15 | 175070668 |
| 16 | 659220634 |
| 17 | 2485025556 |
| 18 | 9378589340 |
| 19 | 35437315784 |
| 20 | 134061346668 |
| 21 | 507765754320 |
| 22 | 1925456658954 |
| 23 | 7309793143626 |
| 24 | 27782162090527 |