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 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 54 |
| 5 | 164 |
| 6 | 508 |
| 7 | 1610 |
| 8 | 5222 |
| 9 | 17308 |
| 10 | 58484 |
| 11 | 200948 |
| 12 | 700348 |
| 13 | 2470472 |
| 14 | 8804024 |
| 15 | 31648858 |
| 16 | 114623366 |
| 17 | 417820972 |
| 18 | 1531629764 |
| 19 | 5642508508 |
| 20 | 20878731476 |
| 21 | 77561756152 |
| 22 | 289156105544 |
| 23 | 1081466311108 |
| 24 | 4056621689564 |
| 25 | 15257327887384 |
| 26 | 57525469116168 |
| 27 | 217383333920040 |
| 28 | 823195469508792 |
| 29 | 3123379468819600 |
| 30 | 11872247508521072 |
| 31 | 45203794091311354 |