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 | 3 |
| 1 | 10 |
| 2 | 38 |
| 3 | 160 |
| 4 | 722 |
| 5 | 3400 |
| 6 | 16418 |
| 7 | 80440 |
| 8 | 397442 |
| 9 | 1973320 |
| 10 | 9825698 |
| 11 | 49007320 |
| 12 | 244676162 |
| 13 | 1222305640 |
| 14 | 6108314978 |
| 15 | 30531959800 |
| 16 | 152631002882 |
| 17 | 763068724360 |
| 18 | 3815084948258 |
| 19 | 19074649113880 |
| 20 | 95370919473602 |
| 21 | 476847620653480 |