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 | 3 |
| 2 | 9 |
| 3 | 39 |
| 4 | 153 |
| 5 | 615 |
| 6 | 2457 |
| 7 | 9831 |
| 8 | 39321 |
| 9 | 157287 |
| 10 | 629145 |
| 11 | 2516583 |
| 12 | 10066329 |
| 13 | 40265319 |
| 14 | 161061273 |
| 15 | 644245095 |
| 16 | 2576980377 |
| 17 | 10307921511 |
| 18 | 41231686041 |
| 19 | 164926744167 |
| 20 | 659706976665 |
| 21 | 2638827906663 |
| 22 | 10555311626649 |
| 23 | 42221246506599 |
| 24 | 168884986026393 |
| 25 | 675539944105575 |