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 | 3 |
| 2 | 9 |
| 3 | 24 |
| 4 | 66 |
| 5 | 174 |
| 6 | 462 |
| 7 | 1206 |
| 8 | 3150 |
| 9 | 8166 |
| 10 | 21150 |
| 11 | 54582 |
| 12 | 140718 |
| 13 | 362118 |
| 14 | 931134 |
| 15 | 2391894 |
| 16 | 6141006 |
| 17 | 15757734 |
| 18 | 40420062 |
| 19 | 103647606 |
| 20 | 265721070 |
| 21 | 681097926 |
| 22 | 1745555070 |
| 23 | 4473092502 |
| 24 | 11461604238 |
| 25 | 29366557158 |
| 26 | 75238139934 |
| 27 | 192754700214 |