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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 12 |
| 5 | 36 |
| 6 | 109 |
| 7 | 328 |
| 8 | 984 |
| 9 | 2952 |
| 10 | 8857 |
| 11 | 26572 |
| 12 | 79716 |
| 13 | 239148 |
| 14 | 717445 |
| 15 | 2152336 |
| 16 | 6457008 |
| 17 | 19371024 |
| 18 | 58113073 |
| 19 | 174339220 |
| 20 | 523017660 |
| 21 | 1569052980 |
| 22 | 4707158941 |
| 23 | 14121476824 |
| 24 | 42364430472 |
| 25 | 127093291416 |