cp's OEIS Frontend

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.

A217124 Semiprimes whose decimal representation has only digits in {4,5,7}.

Table of values

n a(n)
1 4
2 55
3 57
4 74
5 77
6 445
7 447
8 454
9 545
10 554
11 745
12 755
13 4474
14 4555
15 4574
16 4577
17 4747
18 4754
19 4757
20 4777
21 5447
22 5455
23 5545
24 5554
25 5747
26 5755
27 5774
28 5777
29 7445
30 7447
31 7454
32 7555
33 7745
34 7747
35 7754
36 44477
37 44554
38 44557
39 44747
40 44755
41 45447
42 45454
43 45455
44 45457

List of values

[4, 55, 57, 74, 77, 445, 447, 454, 545, 554, 745, 755, 4474, 4555, 4574, 4577, 4747, 4754, 4757, 4777, 5447, 5455, 5545, 5554, 5747, 5755, 5774, 5777, 7445, 7447, 7454, 7555, 7745, 7747, 7754, 44477, 44554, 44557, 44747, 44755, 45447, 45454, 45455, 45457]