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 | 34 |
| 3 | 132 |
| 4 | 722 |
| 5 | 4638 |
| 6 | 32416 |
| 7 | 238956 |
| 8 | 1827918 |
| 9 | 14370595 |
| 10 | 115384756 |
| 11 | 942115942 |
| 12 | 7798224226 |
| 13 | 65286060253 |
| 14 | 551838621972 |
| 15 | 4702955036640 |
| 16 | 40366238473530 |
| 17 | 348631520142879 |
| 18 | 3027590307082804 |
| 19 | 26420699531880832 |
| 20 | 231571468023697960 |
| 21 | 2037650653547067005 |