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 | 1 |
| 3 | 7 |
| 4 | 30 |
| 5 | 148 |
| 6 | 610 |
| 7 | 2823 |
| 8 | 11690 |
| 9 | 52952 |
| 10 | 221094 |
| 11 | 992190 |
| 12 | 4173708 |
| 13 | 18642456 |
| 14 | 78906516 |
| 15 | 351537963 |
| 16 | 1495497690 |
| 17 | 6652572976 |
| 18 | 28420125190 |
| 19 | 126308309058 |
| 20 | 541492971140 |
| 21 | 2405203008440 |
| 22 | 10341957297084 |
| 23 | 45920564571398 |
| 24 | 197952999374468 |