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 | 0 |
| 2 | 3 |
| 3 | 2 |
| 4 | 12 |
| 5 | 24 |
| 6 | 80 |
| 7 | 222 |
| 8 | 687 |
| 9 | 2096 |
| 10 | 6585 |
| 11 | 20892 |
| 12 | 67216 |
| 13 | 218412 |
| 14 | 716304 |
| 15 | 2367696 |
| 16 | 7881381 |
| 17 | 26398728 |
| 18 | 88918451 |
| 19 | 301014786 |
| 20 | 1023681792 |
| 21 | 3495786472 |
| 22 | 11983194420 |
| 23 | 41220422022 |
| 24 | 142247592803 |
| 25 | 492339048156 |
| 26 | 1708741395441 |
| 27 | 5945617039980 |
| 28 | 20737219258440 |
| 29 | 72488490389592 |