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A173127
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a(n) = sinh((2n-1)*arcsinh(3)).
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14
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-3, 3, 117, 4443, 168717, 6406803, 243289797, 9238605483, 350823718557, 13322062699683, 505887558869397, 19210405174337403, 729489509065951917, 27701390939331835443, 1051923366185543794917, 39945386524111332371403
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = (1/2)*((-3+sqrt(10))*(19+6*sqrt(10))^n + (-3-sqrt(10))*(19-6*sqrt(10))^n).
a(n) = -a(-n+1).
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MATHEMATICA
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LinearRecurrence[{38, -1}, {-3, 3}, 30] (* Harvey P. Dale, Jan 14 2015 *)
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PROG
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(Magma) [-3], [n: n in [0..10^7]|IsSquare((n^2+1)/10)]; // Vincenzo Librandi, Jan 02 2012
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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