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A097740
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Chebyshev U(n,x) polynomial evaluated at x=201.
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4
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1, 402, 161603, 64964004, 26115368005, 10498312974006, 4220295700182407, 1696548373160353608, 682008225714761968009, 274165610188961150786010, 110213893287736667854008011, 44305710936059951516160434412
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OFFSET
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0,2
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COMMENTS
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Used to form integer solutions of Pell equation a^2 - 101*b^2 =-1. See A097741 with A097742.
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LINKS
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FORMULA
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a(n) = 2*201*a(n-1) - a(n-2), n>=1, a(0)=1, a(-1):=0.
a(n) = S(n, 2*201)= U(n, 201), Chebyshev's polynomials of the second kind. See A049310.
G.f.: 1/(1-402*x+x^2).
a(n)= sum((-1)^k*binomial(n-k, k)*402^(n-2*k), k=0..floor(n/2)), n>=0.
a(n) = ((201+20*sqrt(101))^(n+1) - (201-20*sqrt(101))^(n+1))/(40*sqrt(101)), n>=0.
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MATHEMATICA
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LinearRecurrence[{402, -1}, {1, 402}, 12] (* Ray Chandler, Aug 11 2015 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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