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 | 1 |
| 2 | 9 |
| 3 | 64 |
| 4 | 465 |
| 5 | 3456 |
| 6 | 26082 |
| 7 | 199060 |
| 8 | 1532313 |
| 9 | 11875015 |
| 10 | 92528414 |
| 11 | 724187982 |
| 12 | 5689127886 |
| 13 | 44834549501 |
| 14 | 354289977750 |
| 15 | 2806262293824 |
| 16 | 22273793685609 |
| 17 | 177113634045858 |
| 18 | 1410633764438967 |
| 19 | 11251419724586850 |
| 20 | 89860413370562730 |
| 21 | 718528004169570925 |