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 | 15 |
| 3 | 54 |
| 4 | 174 |
| 5 | 537 |
| 6 | 1629 |
| 7 | 4908 |
| 8 | 14748 |
| 9 | 44271 |
| 10 | 132843 |
| 11 | 398562 |
| 12 | 1195722 |
| 13 | 3587205 |
| 14 | 10761657 |
| 15 | 32285016 |
| 16 | 96855096 |
| 17 | 290565339 |
| 18 | 871696071 |
| 19 | 2615088270 |
| 20 | 7845264870 |
| 21 | 23535794673 |
| 22 | 70607384085 |
| 23 | 211822152324 |
| 24 | 635466457044 |
| 25 | 1906399371207 |
| 26 | 5719198113699 |
| 27 | 17157594341178 |