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) |
|---|---|
| 3 | 1 |
| 4 | 1 |
| 5 | 5 |
| 6 | 7 |
| 7 | 33 |
| 8 | 57 |
| 9 | 279 |
| 10 | 561 |
| 11 | 2895 |
| 12 | 6555 |
| 13 | 35685 |
| 14 | 89055 |
| 15 | 509985 |
| 16 | 1381905 |
| 17 | 8294895 |
| 18 | 24137505 |
| 19 | 151335135 |
| 20 | 468934515 |
| 21 | 3061162125 |
| 22 | 10033419375 |
| 23 | 68000295825 |
| 24 | 234484536825 |
| 25 | 1645756410375 |
| 26 | 5943863027025 |
| 27 | 43105900812975 |
| 28 | 162446292283275 |
| 29 | 1214871076343925 |
| 30 | 4761954230608575 |