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 | 1 |
| 5 | 9 |
| 6 | 29 |
| 7 | 112 |
| 8 | 405 |
| 9 | 1514 |
| 10 | 5565 |
| 11 | 20249 |
| 12 | 73416 |
| 13 | 265616 |
| 14 | 957677 |
| 15 | 3441282 |
| 16 | 12329838 |
| 17 | 44062706 |
| 18 | 157105923 |
| 19 | 559009643 |
| 20 | 1985301783 |
| 21 | 7038496811 |
| 22 | 24913917722 |
| 23 | 88058727525 |
| 24 | 310832221932 |
| 25 | 1095854282575 |
| 26 | 3859201682187 |
| 27 | 13576884290502 |
| 28 | 47719628447310 |
| 29 | 167579774234059 |