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Leyland numbers (Cubes), a^b+b^a, a and b > 1.
0

%I #2 Mar 31 2012 12:38:28

%S 8,512,

%T 1056589062271330492704679569833033213037694652072243044255921418053347805113449718948834511775314375789348789986514257357764695119005371074501077956925879153816773367998010168337463035352852882106048465816422376808296056585503123477676793797534072952979077161795475996672

%N Leyland numbers (Cubes), a^b+b^a, a and b > 1.

%e 2^3=8, 8^3=512,

%e 101851798816724304313422284420468908052573419683296812531807022467719064988166\

%e 8353091698688^3=1056...6672

%t f[a_,b_]:=a^b+b^a; Select[Union[Flatten[Table[f[a,b],{a,2,150},{b,2,150}]]],IntegerQ[(#1)^(1/3)]&]

%Y Cf. A076980, A173054, A173055, A173056

%K nonn,bref

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Feb 08 2010