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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 18 |
| 6 | 64 |
| 7 | 227 |
| 8 | 856 |
| 9 | 3280 |
| 10 | 12885 |
| 11 | 51342 |
| 12 | 207544 |
| 13 | 847886 |
| 14 | 3497384 |
| 15 | 14541132 |
| 16 | 60884173 |
| 17 | 256480895 |
| 18 | 1086310549 |
| 19 | 4623128656 |
| 20 | 19759964149 |
| 21 | 84784735379 |
| 22 | 365066645854 |
| 23 | 1576927900803 |
| 24 | 6831518134251 |
| 25 | 29674505668536 |
| 26 | 129216630647787 |
| 27 | 563949605921815 |