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) |
|---|---|
| 2 | 4 |
| 3 | 12 |
| 4 | 52 |
| 5 | 172 |
| 6 | 580 |
| 7 | 1852 |
| 8 | 5828 |
| 9 | 17980 |
| 10 | 54788 |
| 11 | 165116 |
| 12 | 493316 |
| 13 | 1463036 |
| 14 | 4312068 |
| 15 | 12641276 |
| 16 | 36887556 |
| 17 | 107201532 |
| 18 | 310427652 |
| 19 | 896045052 |
| 20 | 2579017732 |
| 21 | 7403843580 |
| 22 | 21205303300 |
| 23 | 60604891132 |
| 24 | 172872744964 |
| 25 | 492233179132 |
| 26 | 1399272374276 |