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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 9 |
| 5 | 36 |
| 6 | 112 |
| 7 | 428 |
| 8 | 1505 |
| 9 | 5692 |
| 10 | 21026 |
| 11 | 79806 |
| 12 | 301488 |
| 13 | 1151866 |
| 14 | 4403778 |
| 15 | 16929474 |
| 16 | 65204353 |
| 17 | 251947668 |
| 18 | 975366094 |
| 19 | 3784197606 |
| 20 | 14705937794 |
| 21 | 57242631464 |
| 22 | 223121176224 |
| 23 | 870805992278 |
| 24 | 3402485053664 |
| 25 | 13308485156086 |
| 26 | 52104519751272 |
| 27 | 204176144516818 |