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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.

A118690 Semiprimes for which both the sum and the product of the digits is also a semiprime.

Table of values

n a(n)
1 4
2 6
3 9
4 22
5 33
6 55
7 77
8 91
9 123
10 141
11 177
12 213
13 217
14 321
15 411
16 717
17 721
18 771
19 1135
20 1157
21 1315
22 1351
23 1513
24 1517
25 1751
26 3151
27 5131
28 5311
29 7115
30 11157
31 11215
32 11521
33 11611
34 11751
35 12115
36 12151
37 15117
38 15711
39 17151
40 21151
41 51211
42 57111
43 61111
44 75111

List of values

[4, 6, 9, 22, 33, 55, 77, 91, 123, 141, 177, 213, 217, 321, 411, 717, 721, 771, 1135, 1157, 1315, 1351, 1513, 1517, 1751, 3151, 5131, 5311, 7115, 11157, 11215, 11521, 11611, 11751, 12115, 12151, 15117, 15711, 17151, 21151, 51211, 57111, 61111, 75111]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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