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 | 1 |
| 2 | 1 |
| 3 | 9 |
| 4 | 45 |
| 5 | 248 |
| 6 | 1377 |
| 7 | 7756 |
| 8 | 44096 |
| 9 | 252570 |
| 10 | 1455166 |
| 11 | 8424011 |
| 12 | 48960606 |
| 13 | 285512823 |
| 14 | 1669721225 |
| 15 | 9788890230 |
| 16 | 57511916805 |
| 17 | 338536358979 |
| 18 | 1996103321754 |
| 19 | 11787262391390 |
| 20 | 69699393574522 |