%I #10 Sep 09 2021 11:26:06
%S 25,35,57,235,237,253,327,527,537,573,723,753,2537,2573,2735,5327,
%T 5723,7235
%N Semiprimes formed from single-digits primes only, each used at most once.
%e 527 is a semiprime and its non-repeating digits are primes.
%t Select[FromDigits/@Flatten[Permutations/@Subsets[ {2,3,5,7}],1],PrimeOmega[ #] == 2&]//Union
%Y Cf. A177061, A000040, A168349, A168385.
%K easy,base,fini,full,nonn
%O 1,1
%A _Harvey P. Dale_, Sep 08 2021