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 | 5 |
| 3 | 48 |
| 4 | 423 |
| 5 | 3082 |
| 6 | 18998 |
| 7 | 133083 |
| 8 | 965175 |
| 9 | 6907447 |
| 10 | 48357538 |
| 11 | 337492571 |
| 12 | 2379164196 |
| 13 | 16812509746 |
| 14 | 118525108279 |
| 15 | 834050273099 |
| 16 | 5871294215587 |
| 17 | 41366373307538 |
| 18 | 291469733924989 |
| 19 | 2053121255070040 |
| 20 | 14460522145205162 |
| 21 | 101855876591455305 |
| 22 | 717493569094700741 |