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%I #20 Nov 04 2013 14:31:51
%S 108,1024,6912,12500,84375,186624,800000,1259712,3294172,11943936,
%T 22235661,67108864,145800000,210827008,452984832,1549681956,
%U 2573571875,4294967296,10460353203,38423222208,40000000000,52428800000,99179645184,270000000000,782757789696
%N Numbers representable as x^x * y^y, with x > y > 1.
%C A subsequence of A156223.
%e a(7) = 4^4 * 5^5 = 800000.
%t nn = 12; Select[Rest[Union[Flatten[Table[If[x > y, x^x*y^y, 0], {x, 3, nn}, {y, 2, nn - 1}]]]], # <= 4*nn^nn &] (* _T. D. Noe_, Nov 04 2013 *)
%Y Cf. A000312, A156223.
%K nonn
%O 1,1
%A _Alex Ratushnyak_, Nov 02 2013