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) |
|---|---|
| 3 | 1 |
| 4 | 4 |
| 5 | 15 |
| 6 | 53 |
| 7 | 182 |
| 8 | 616 |
| 9 | 2070 |
| 10 | 6930 |
| 11 | 23166 |
| 12 | 77429 |
| 13 | 258973 |
| 14 | 867230 |
| 15 | 2908633 |
| 16 | 9772556 |
| 17 | 32896088 |
| 18 | 110949072 |
| 19 | 374934201 |
| 20 | 1269505482 |
| 21 | 4306750577 |
| 22 | 14638006449 |
| 23 | 49843505965 |
| 24 | 170021694271 |
| 25 | 580954640775 |
| 26 | 1988357053020 |
| 27 | 6816047416230 |
| 28 | 23400699072231 |
| 29 | 80455436055699 |