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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 11 |
| 5 | 52 |
| 6 | 287 |
| 7 | 1871 |
| 8 | 14034 |
| 9 | 119292 |
| 10 | 1133278 |
| 11 | 11899423 |
| 12 | 136843365 |
| 13 | 1710542068 |
| 14 | 23092317922 |
| 15 | 334838609873 |
| 16 | 5189998453040 |
| 17 | 85634974475162 |
| 18 | 1498612053315336 |
| 19 | 27724322986333718 |
| 20 | 540624298233507504 |