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) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 29 |
| 5 | 132 |
| 6 | 591 |
| 7 | 2648 |
| 8 | 11970 |
| 9 | 54818 |
| 10 | 254868 |
| 11 | 1204042 |
| 12 | 5779861 |
| 13 | 28178306 |
| 14 | 139394333 |
| 15 | 698911166 |
| 16 | 3547422416 |
| 17 | 18204441884 |
| 18 | 94339586414 |
| 19 | 493148411592 |
| 20 | 2597699326194 |
| 21 | 13776442755524 |
| 22 | 73498738275926 |
| 23 | 394203045846692 |