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 | 20 |
| 4 | 71 |
| 5 | 258 |
| 6 | 954 |
| 7 | 3572 |
| 8 | 13501 |
| 9 | 51404 |
| 10 | 196858 |
| 11 | 757472 |
| 12 | 2926097 |
| 13 | 11341032 |
| 14 | 44080770 |
| 15 | 171755976 |
| 16 | 670664951 |
| 17 | 2623732322 |
| 18 | 10281616176 |
| 19 | 40350944112 |
| 20 | 158573538071 |
| 21 | 623930435834 |
| 22 | 2457658576132 |
| 23 | 9690467310480 |
| 24 | 38244489565051 |
| 25 | 151064227161784 |
| 26 | 597165099484632 |