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%I #6 Jan 03 2017 03:04:02
%S 25,125,127,128,216,289,343,347,625,736,1285,1296,1792,2048,2187
%N Integers that can be written using their individual decimal digits and the operations + - * / ^ but not the concatenation of their digits.
%C A proper subset of A036057.
%e 125 is in the sequence since 5^(1+2) but 121 is not in the sequence. We do not accept 11^2 since 11 is the concatenation of two digits.
%t ops = {Plus, Subtract, Times, Divide, Power}; fQ[n_] := Length@ Select[ Groupings[ Permutations@ IntegerDigits@ n, ops -> 2], # == n &] > 0; k = 1; lst = {}; While[k < 1001, If[fQ@k, AppendTo[lst, k]]; k++]; lst (* requires Mathematica version 11 or better *)
%Y Cf. A036057.
%K base,nonn
%O 1,1
%A _Erich Friedman_ and _Robert G. Wilson v_, Jan 01 2017