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 | 2 |
| 2 | 10 |
| 3 | 38 |
| 4 | 130 |
| 5 | 422 |
| 6 | 1330 |
| 7 | 4118 |
| 8 | 12610 |
| 9 | 38342 |
| 10 | 116050 |
| 11 | 350198 |
| 12 | 1054690 |
| 13 | 3172262 |
| 14 | 9533170 |
| 15 | 28632278 |
| 16 | 85962370 |
| 17 | 258018182 |
| 18 | 774316690 |
| 19 | 2323474358 |
| 20 | 6971471650 |
| 21 | 20916512102 |
| 22 | 62753730610 |
| 23 | 188269580438 |
| 24 | 564825518530 |
| 25 | 1694510110022 |
| 26 | 5083597438930 |
| 27 | 15250926534518 |
| 28 | 45753048039010 |