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) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 19 |
| 7 | 69 |
| 8 | 252 |
| 9 | 855 |
| 10 | 2867 |
| 11 | 9339 |
| 12 | 30085 |
| 13 | 95524 |
| 14 | 300796 |
| 15 | 939228 |
| 16 | 2915481 |
| 17 | 9001380 |
| 18 | 27675779 |
| 19 | 84782673 |
| 20 | 258956584 |
| 21 | 788926699 |
| 22 | 2398385803 |
| 23 | 7277878707 |
| 24 | 22050326805 |
| 25 | 66718218120 |
| 26 | 201640080056 |
| 27 | 608808949752 |
| 28 | 1836608777233 |
| 29 | 5536482441124 |
| 30 | 16679237438035 |