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 | 6 |
| 2 | 24 |
| 3 | 90 |
| 4 | 318 |
| 5 | 1098 |
| 6 | 3696 |
| 7 | 12270 |
| 8 | 40224 |
| 9 | 130650 |
| 10 | 421176 |
| 11 | 1348998 |
| 12 | 4299018 |
| 13 | 13635630 |
| 14 | 43092888 |
| 15 | 135698970 |
| 16 | 426144654 |
| 17 | 1334488074 |
| 18 | 4170038328 |
| 19 | 13001153910 |
| 20 | 40464412482 |
| 21 | 125706293478 |
| 22 | 389962873920 |
| 23 | 1207855307874 |
| 24 | 3736709089176 |
| 25 | 11544946664622 |
| 26 | 35633199126576 |