A287534 Composite numbers whose digits are restricted to 1, 3, 7, and 9.

9, 33, 39, 77, 91, 93, 99, 111, 113, 117, 119, 133, 171, 177, 319, 333, 339, 371, 377, 391, 393, 399, 711, 713, 717, 731, 737, 771, 777, 779, 791, 793, 799, 913, 917, 931, 933, 939, 973, 979, 993, 999

Offset: 1

Author

Luke Zieroth, May 26 2017

Keywords

• nonn
• base

Crossrefs

Cf. A091633, A136333.

Programs

Mathematica

Select[Flatten@ Array[FromDigits /@ Tuples[{1, 3, 7, 9}, #] &, 3], CompositeQ] (* Michael De Vlieger, Jun 01 2017 *)