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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 21 |
| 7 | 84 |
| 8 | 327 |
| 9 | 1251 |
| 10 | 4760 |
| 11 | 18018 |
| 12 | 68104 |
| 13 | 257088 |
| 14 | 970480 |
| 15 | 3664070 |
| 16 | 13842215 |
| 17 | 52331695 |
| 18 | 198021936 |
| 19 | 750027090 |
| 20 | 2843686271 |
| 21 | 10792866315 |
| 22 | 41006110365 |
| 23 | 155961264880 |
| 24 | 593797895358 |
| 25 | 2263126224780 |
| 26 | 8634161689920 |
| 27 | 32973466762098 |
| 28 | 126047166461574 |
| 29 | 482298648250416 |
| 30 | 1847156083546316 |