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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 9 |
| 5 | 31 |
| 6 | 91 |
| 7 | 309 |
| 8 | 1009 |
| 9 | 3481 |
| 10 | 11956 |
| 11 | 42065 |
| 12 | 148655 |
| 13 | 532039 |
| 14 | 1915369 |
| 15 | 6950452 |
| 16 | 25357233 |
| 17 | 93034813 |
| 18 | 342888250 |
| 19 | 1269246437 |
| 20 | 4715945712 |
| 21 | 17583623988 |
| 22 | 65766726906 |
| 23 | 246694006971 |
| 24 | 927801717255 |
| 25 | 3497918129001 |
| 26 | 13217196871126 |
| 27 | 50046561077947 |