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 | 0 |
| 3 | 6 |
| 4 | 36 |
| 5 | 210 |
| 6 | 1452 |
| 7 | 12138 |
| 8 | 114684 |
| 9 | 1147002 |
| 10 | 11729148 |
| 11 | 120902202 |
| 12 | 1249686492 |
| 13 | 12929303130 |
| 14 | 133809210108 |
| 15 | 1384977143610 |
| 16 | 14335551770268 |
| 17 | 148385432561562 |
| 18 | 1535924231893308 |
| 19 | 15898233466089210 |
| 20 | 164561459781232092 |
| 21 | 1703363953470584922 |
| 22 | 17631399812695032444 |