A383934 Composite numbers that contain only nonprime digits and whose prime factors contain only nonprime digits.
1111, 1199, 1681, 1691, 1919, 1991, 4141, 4411, 4469, 4499, 4609, 4961, 6109, 6161, 6611, 6649, 6809, 8899, 8989, 9089, 9481, 9691, 10109, 10901, 11009, 11041, 11099, 11419, 11881, 14641, 14801, 16109, 16441, 16489, 16999, 18409, 18491, 18601, 18689
Offset: 1
Examples
10109 is a term as 10109 = 11 * 919, and both the number and its prime factors only contain nonprime digits.
Links
- Scott R. Shannon, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Select[Select[Range[20000], And[CompositeQ[#], NoneTrue[IntegerDigits[#], PrimeQ]] &], NoneTrue[Flatten[IntegerDigits /@ FactorInteger[#][[All, 1]] ], PrimeQ] &] (* Michael De Vlieger, Aug 23 2025 *)