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 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 21 |
| 6 | 53 |
| 7 | 155 |
| 8 | 449 |
| 9 | 1273 |
| 10 | 3721 |
| 11 | 11155 |
| 12 | 33529 |
| 13 | 101245 |
| 14 | 309037 |
| 15 | 950587 |
| 16 | 2936833 |
| 17 | 9117169 |
| 18 | 28448209 |
| 19 | 89134435 |
| 20 | 280252585 |
| 21 | 884123429 |
| 22 | 2797933733 |
| 23 | 8879167067 |
| 24 | 28249550913 |
| 25 | 90091462761 |
| 26 | 287946752601 |
| 27 | 922194331891 |
| 28 | 2959055180953 |
| 29 | 9511538457229 |