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 | 3 |
| 2 | 13 |
| 3 | 49 |
| 4 | 180 |
| 5 | 662 |
| 6 | 2430 |
| 7 | 8910 |
| 8 | 32671 |
| 9 | 119796 |
| 10 | 439252 |
| 11 | 1610592 |
| 12 | 5905506 |
| 13 | 21653524 |
| 14 | 79396256 |
| 15 | 291119607 |
| 16 | 1067438559 |
| 17 | 3913941385 |
| 18 | 14351118413 |
| 19 | 52620767516 |
| 20 | 192942814227 |
| 21 | 707456985499 |
| 22 | 2594008946832 |
| 23 | 9511366138386 |