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 | 3 |
| 4 | 9 |
| 5 | 25 |
| 6 | 70 |
| 7 | 196 |
| 8 | 552 |
| 9 | 1560 |
| 10 | 4423 |
| 11 | 12573 |
| 12 | 35826 |
| 13 | 102310 |
| 14 | 292786 |
| 15 | 839554 |
| 16 | 2411945 |
| 17 | 6941593 |
| 18 | 20011328 |
| 19 | 57779038 |
| 20 | 167069317 |
| 21 | 483739961 |
| 22 | 1402413161 |
| 23 | 4070537585 |
| 24 | 11827842021 |
| 25 | 34403798725 |
| 26 | 100167396088 |
| 27 | 291903951462 |
| 28 | 851380987390 |
| 29 | 2485175809878 |