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 | 1 |
| 1 | 4 |
| 2 | 15 |
| 3 | 56 |
| 4 | 211 |
| 5 | 798 |
| 6 | 3030 |
| 7 | 11550 |
| 8 | 44193 |
| 9 | 169652 |
| 10 | 653158 |
| 11 | 2521038 |
| 12 | 9752516 |
| 13 | 37802636 |
| 14 | 146792136 |
| 15 | 570924940 |
| 16 | 2223730395 |
| 17 | 8672669484 |
| 18 | 33864089798 |
| 19 | 132372227670 |
| 20 | 517947357111 |
| 21 | 2028479976186 |
| 22 | 7950990968079 |
| 23 | 31189593428478 |