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 | 16 |
| 3 | 72 |
| 4 | 352 |
| 5 | 1816 |
| 6 | 9728 |
| 7 | 53584 |
| 8 | 301568 |
| 9 | 1726488 |
| 10 | 10022912 |
| 11 | 58864240 |
| 12 | 349102080 |
| 13 | 2087772784 |
| 14 | 12576358400 |
| 15 | 76237953440 |
| 16 | 464736354304 |
| 17 | 2847019090712 |
| 18 | 17518413479936 |
| 19 | 108224749140784 |
| 20 | 670996707147776 |
| 21 | 4173817417204944 |
| 22 | 26040046909915136 |
| 23 | 162905940337309792 |
| 24 | 1021700454913933312 |