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 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 23 |
| 6 | 67 |
| 7 | 222 |
| 8 | 832 |
| 9 | 3501 |
| 10 | 16412 |
| 11 | 85062 |
| 12 | 484013 |
| 13 | 3004342 |
| 14 | 20226212 |
| 15 | 146930527 |
| 16 | 1146389206 |
| 17 | 9566847302 |
| 18 | 85073695846 |
| 19 | 803417121866 |
| 20 | 8032911742979 |
| 21 | 84796557160893 |
| 22 | 942648626858310 |
| 23 | 11009672174119829 |
| 24 | 134809696481902160 |
| 25 | 1727161011322322267 |
| 26 | 23110946295566466698 |
| 27 | 322435363123261622935 |