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) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 18 |
| 4 | 66 |
| 5 | 202 |
| 6 | 730 |
| 7 | 2036 |
| 8 | 7488 |
| 9 | 19262 |
| 10 | 62772 |
| 11 | 190408 |
| 12 | 1077600 |
| 13 | 2185196 |
| 14 | 12081408 |
| 15 | 21927244 |
| 16 | 52980770 |
| 17 | 148851716 |
| 18 | 1353060240 |
| 19 | 2585159746 |
| 20 | 16942421808 |
| 21 | 28793485330 |
| 22 | 51092435876 |
| 23 | 106822624510 |
| 24 | 1565885020128 |