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 | 9 |
| 2 | 39 |
| 3 | 175 |
| 4 | 793 |
| 5 | 3611 |
| 6 | 16475 |
| 7 | 75229 |
| 8 | 343633 |
| 9 | 1569883 |
| 10 | 7172423 |
| 11 | 32769925 |
| 12 | 149723361 |
| 13 | 684077955 |
| 14 | 3125520983 |
| 15 | 14280373781 |
| 16 | 65246447425 |
| 17 | 298108406323 |
| 18 | 1362045450407 |
| 19 | 6223131628517 |
| 20 | 28433241805745 |
| 21 | 129910355608771 |