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 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 21 |
| 5 | 53 |
| 6 | 159 |
| 7 | 419 |
| 8 | 1257 |
| 9 | 3401 |
| 10 | 10203 |
| 11 | 28095 |
| 12 | 84285 |
| 13 | 235005 |
| 14 | 705015 |
| 15 | 1984155 |
| 16 | 5952465 |
| 17 | 16873745 |
| 18 | 50621235 |
| 19 | 144327287 |
| 20 | 432981861 |
| 21 | 1240296773 |
| 22 | 3720890319 |
| 23 | 10700364691 |
| 24 | 32101094073 |
| 25 | 92619680089 |
| 26 | 277859040267 |
| 27 | 803956981807 |
| 28 | 2411870945421 |
| 29 | 6995553520653 |
| 30 | 20986660561959 |
| 31 | 61001041404555 |