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%I #29 May 17 2015 11:31:38
%S 4,6,9,14,15,22,25,26,33,34,35,38,39,46,49,51,55,57,58,62,69,77,85,93,
%T 94,111,115,118,119,122,123,129,133,134,143,145,146,155,158,159,166,
%U 169,177,178,185,187,202,205,206,213,219,221,226,235,237,247,249,253
%N Semiprimes that are also semiprime when their digits are sorted into nondecreasing order.
%C This is to A211654 primes that are also prime when their digits are sorted into nondecreasing order as A001358 semiprimes are to A000040 primes. There is an ambiguity arising from OEIS conventions, exemplified by the semiprime 303, which sorts to 033 and truncates to the semiprime 33.
%H Alois P. Heinz, <a href="/A182150/b182150.txt">Table of n, a(n) for n = 1..1000</a>
%e 51 is in the sequence because, though it is a semiprime whose digits are in descending order, once the digits are sorted to be nondecreasing, it is the semiprime 15, whose digits are (left to right) nondecreasing.
%p h:= proc(m) local k; for k from m+1 while isprime(k) or
%p add(i[2], i=ifactors(k)[2])<>2 do od; k
%p end:
%p a:= proc(n) option remember; local k, l, s;
%p k:= h(a(n-1));
%p do l:= sort(convert(k, base, 10));
%p s:= add(l[i]*10^(nops(l)-i), i=1..nops(l));
%p if h(s-1)=s then return k else k:=h(k) fi
%p od
%p end: a(0):=0:
%p seq(a(n), n=1..100); # _Alois P. Heinz_, Apr 22 2012
%t Select[Range[300],PrimeOmega[#]==2&&PrimeOmega[FromDigits[ Sort[ IntegerDigits[ #]]]]==2&] (* _Harvey P. Dale_, Nov 13 2014 *)
%Y Cf. A001358, A097393, A211654.
%K nonn,base,easy
%O 1,1
%A _Jonathan Vos Post_, Apr 18 2012
%E More terms from _Alois P. Heinz_, Apr 22 2012
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