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 | 6 |
| 2 | 30 |
| 3 | 138 |
| 4 | 606 |
| 5 | 2586 |
| 6 | 10830 |
| 7 | 44778 |
| 8 | 183486 |
| 9 | 747066 |
| 10 | 3027630 |
| 11 | 12228618 |
| 12 | 49268766 |
| 13 | 198137946 |
| 14 | 795740430 |
| 15 | 3192527658 |
| 16 | 12798808446 |
| 17 | 51281327226 |
| 18 | 205383589230 |
| 19 | 822309197898 |
| 20 | 3291561314526 |
| 21 | 13173218826906 |
| 22 | 52713796014030 |
| 23 | 210917946175338 |
| 24 | 843860071059006 |
| 25 | 3376005143308986 |
| 26 | 13505715150454830 |