n | a(n) |
---|---|
1 | 7 |
2 | 47 |
3 | 4447 |
4 | 7477 |
5 | 44777 |
6 | 47777 |
7 | 74747 |
8 | 77447 |
9 | 77477 |
10 | 77747 |
11 | 4444747 |
12 | 4447747 |
13 | 4747747 |
14 | 4774477 |
15 | 4774747 |
16 | 7444477 |
17 | 7447777 |
18 | 7474477 |
19 | 7477777 |
20 | 7747477 |
21 | 7774777 |
22 | 7777447 |
23 | 44447747 |
24 | 44747447 |
25 | 44747777 |
26 | 44774777 |
27 | 47447747 |
28 | 47774477 |
29 | 47774747 |
[7,47,4447,7477,44777,47777,74747,77447,77477, 77747,4444747,4447747,4747747,4774477,4774747, 7444477,7447777,7474477,7477777,7747477,7774777, 7777447,44447747,44747447,44747777,44774777, 47447747,47774477,47774747] |