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A322890
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a(n) = value of Chebyshev T-polynomial T_n(20).
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2
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1, 20, 799, 31940, 1276801, 51040100, 2040327199, 81562047860, 3260441587201, 130336101440180, 5210183616019999, 208277008539359780, 8325870157958371201, 332826529309795488260, 13304735302233861159199, 531856585560044650879700
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OFFSET
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0,2
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LINKS
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FORMULA
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a(0) = 1, a(1) = 20 and a(n) = 40*a(n-1) - a(n-2) for n > 1.
G.f.: (1 - 20*x) / (1 - 40*x + x^2).
a(n) = ((20+sqrt(399))^(-n) * (1+(20+sqrt(399))^(2*n))) / 2.
(End)
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MAPLE
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seq(coeff(series((1-20*x)/(1-40*x+x^2), x, n+1), x, n), n = 0 .. 20); # Muniru A Asiru, Dec 31 2018
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MATHEMATICA
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CoefficientList[Series[(1 - 20 x)/(1 - 40 x + x^2), {x, 0, 15}], x] (* or *)
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PROG
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(PARI) {a(n) = polchebyshev(n, 1, 20)}
(PARI) Vec((1 - 20*x) / (1 - 40*x + x^2) + O(x^20)) \\ Colin Barker, Dec 30 2018
(GAP) a:=[1, 20];; for n in [3..20] do a[n]:=40*a[n-1]-a[n-2]; od; Print(a); # Muniru A Asiru, Dec 31 2018
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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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