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 | 7 |
| 2 | 34 |
| 3 | 153 |
| 4 | 686 |
| 5 | 3088 |
| 6 | 13917 |
| 7 | 62721 |
| 8 | 282646 |
| 9 | 1273690 |
| 10 | 5739647 |
| 11 | 25864698 |
| 12 | 116554700 |
| 13 | 525233175 |
| 14 | 2366870474 |
| 15 | 10665883415 |
| 16 | 48063918336 |
| 17 | 216591552484 |
| 18 | 976031547888 |
| 19 | 4398313653120 |
| 20 | 19820223058176 |
| 21 | 89316331907533 |