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) |
|---|---|
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 50 |
| 6 | 140 |
| 7 | 392 |
| 8 | 1106 |
| 9 | 3138 |
| 10 | 8952 |
| 11 | 25652 |
| 12 | 73788 |
| 13 | 212940 |
| 14 | 616226 |
| 15 | 1787606 |
| 16 | 5196626 |
| 17 | 15134930 |
| 18 | 44152808 |
| 19 | 128996852 |
| 20 | 377379368 |
| 21 | 1105350728 |
| 22 | 3241135526 |
| 23 | 9513228122 |
| 24 | 27948336380 |
| 25 | 82176836300 |
| 26 | 241813226150 |
| 27 | 712070156202 |
| 28 | 2098240353906 |
| 29 | 6186675630818 |