A344468 Semiprimes k such that every permutation of the digits of k is a semiprime.

4, 6, 9, 15, 22, 26, 33, 39, 49, 51, 55, 58, 62, 77, 85, 93, 94, 111, 155, 177, 178, 187, 226, 262, 339, 355, 393, 515, 535, 551, 553, 622, 717, 718, 771, 781, 817, 871, 899, 933, 989, 998, 1111, 3777, 4555, 5455, 5545, 5554, 5999, 7377, 7737, 7773, 7999, 9599

Offset: 1

Author

Ctibor O. Zizka, May 20 2021

Keywords

• nonn
• base

Examples

			k = 15, A001222(15) = A001222(51) = 2, thus 15 and 51 are terms;
k = 178, A001222(178) = A001222(187) = A001222(718) = A001222(781) = A001222(817) = A001222(871) = 2, thus 178, 187, 718, 781, 817, 871 are terms.
		

Crossrefs

Cf. A000005, A001222, A001358, A003459.

Subsequence of A085751 and A263106.

Programs

Mathematica

q[n_] := AllTrue[Permutations[IntegerDigits[n]], PrimeOmega[FromDigits[#]] == 2 &]; Select[Range[10^4], q] (* Amiram Eldar, May 20 2021 *)