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 | 2 |
| 3 | 4 |
| 4 | 2 |
| 5 | 4 |
| 6 | 4 |
| 7 | 8 |
| 8 | 18 |
| 9 | 52 |
| 10 | 164 |
| 11 | 544 |
| 12 | 1852 |
| 13 | 6416 |
| 14 | 22520 |
| 15 | 79888 |
| 16 | 285938 |
| 17 | 1031316 |
| 18 | 3744628 |
| 19 | 13676384 |
| 20 | 50209860 |
| 21 | 185190400 |
| 22 | 685888736 |
| 23 | 2549873880 |
| 24 | 9511787452 |
| 25 | 35592025904 |
| 26 | 133559834064 |
| 27 | 502494233128 |
| 28 | 1895089009088 |
| 29 | 7162963968712 |