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 | 2 |
| 3 | 5 |
| 4 | 20 |
| 5 | 68 |
| 6 | 241 |
| 7 | 844 |
| 8 | 2966 |
| 9 | 10413 |
| 10 | 36568 |
| 11 | 128408 |
| 12 | 450913 |
| 13 | 1583400 |
| 14 | 5560186 |
| 15 | 19524853 |
| 16 | 68562444 |
| 17 | 240760252 |
| 18 | 845440977 |
| 19 | 2968805844 |
| 20 | 10425101678 |
| 21 | 36608235997 |
| 22 | 128551546480 |
| 23 | 451414815600 |
| 24 | 1585164405441 |
| 25 | 5566379537040 |