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A088037
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Smallest square k == 1 (mod some n-th power), k > 1.
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2
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4, 9, 9, 49, 225, 961, 3969, 16129, 65025, 261121, 1046529, 4190209, 16769025, 67092481, 268402689, 1073676289, 4294836225, 17179607041, 68718952449, 274876858369, 1099509530625, 4398042316801, 17592177655809
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OFFSET
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1,1
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COMMENTS
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From a(2) onwards the n-th power that divides a(n) -1 is 2^n ===> Second term onwards same as A060867 i.e. a(n+1) = (2^n-1)^2.
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LINKS
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FORMULA
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a(n) = (2^n-2)^2/4 for n>2.
a(n) = 7*a(n-1)-14*a(n-2)+8*a(n-3) for n>5.
G.f.: x*(2*x+1)*(32*x^3-56*x^2+27*x-4) / ((x-1)*(2*x-1)*(4*x-1)). (End)
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EXAMPLE
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a(6) = 961 and 960 = 64*15.
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CROSSREFS
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KEYWORD
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nonn,easy,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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