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 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 7 |
| 7 | 21 |
| 8 | 61 |
| 9 | 184 |
| 10 | 573 |
| 11 | 1835 |
| 12 | 5969 |
| 13 | 19715 |
| 14 | 66054 |
| 15 | 223971 |
| 16 | 767174 |
| 17 | 2651771 |
| 18 | 9240766 |
| 19 | 32436016 |
| 20 | 114596715 |
| 21 | 407263306 |
| 22 | 1455145050 |
| 23 | 5224710466 |
| 24 | 18843677124 |
| 25 | 68243466611 |
| 26 | 248090964092 |
| 27 | 905092211818 |
| 28 | 3312816854525 |
| 29 | 12162610429661 |
| 30 | 44780896121875 |
| 31 | 165316324574671 |
| 32 | 611819769698967 |