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A188982
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Even numbers x such that x^2 + y^2 = 13^n with x and y coprime.
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4
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0, 2, 12, 46, 120, 122, 828, 6554, 28560, 86158, 145668, 246046, 3369960, 17021162, 58317492, 128629846, 13651680, 1590277918, 9719139348, 37641223154, 99498527400, 107655263398, 647549275812, 5284814079046, 23290743888720, 71041880304722, 123471611274972, 182714776311554, 2701419604443960, 13833225534613558, 47880898349909868
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OFFSET
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0,2
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COMMENTS
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This is also the absolute value of the imaginary part of (3+2i)^n, where i = sqrt(-1).
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LINKS
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MATHEMATICA
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Table[s = Select[PowersRepresentations[13^n, 2, 2], CoprimeQ @@ # &, 1][[1]]; Select[s, EvenQ][[1]], {n, 0, 30}]
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PROG
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(Magma) [Integers()!Abs(Im((3+2*Sqrt(-1))^n)): n in [0..30]]; // Bruno Berselli, May 26 2011
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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