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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 12 |
| 4 | 75 |
| 5 | 329 |
| 6 | 1158 |
| 7 | 3606 |
| 8 | 10971 |
| 9 | 35601 |
| 10 | 126168 |
| 11 | 467541 |
| 12 | 1722714 |
| 13 | 6173070 |
| 14 | 21563906 |
| 15 | 74452230 |
| 16 | 257613930 |
| 17 | 899546303 |
| 18 | 3166966692 |
| 19 | 11185908147 |
| 20 | 39459021883 |
| 21 | 138761604786 |
| 22 | 486746839758 |
| 23 | 1705955898935 |
| 24 | 5982257083623 |
| 25 | 20999661326520 |
| 26 | 73772324787965 |