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 | 2 |
| 2 | 8 |
| 3 | 40 |
| 4 | 192 |
| 5 | 864 |
| 6 | 3712 |
| 7 | 15488 |
| 8 | 63488 |
| 9 | 257536 |
| 10 | 1038336 |
| 11 | 4171776 |
| 12 | 16728064 |
| 13 | 67002368 |
| 14 | 268206080 |
| 15 | 1073250304 |
| 16 | 4293918720 |
| 17 | 17177640960 |
| 18 | 68714758144 |
| 19 | 274867945472 |
| 20 | 1099490656256 |
| 21 | 4398002470912 |
| 22 | 17592093769728 |
| 23 | 70368551239680 |
| 24 | 281474574057472 |
| 25 | 1125899067981824 |