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A077248
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Combined Diophantine Chebyshev sequences A077246 and A077244.
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3
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2, 3, 13, 22, 102, 173, 803, 1362, 6322, 10723, 49773, 84422, 391862, 664653, 3085123, 5232802, 24289122, 41197763, 191227853, 324349302, 1505533702, 2553596653, 11853041763, 20104423922, 93318800402
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OFFSET
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0,1
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COMMENTS
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3*a(n)^2 - 5*b(n)^2 = 7, with the companion sequence b(n)= A077247(n).
Positive values of x (or y) satisfying x^2 - 8xy + y^2 + 35 = 0. - Colin Barker, Feb 08 2014
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LINKS
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FORMULA
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G.f.: (1-x)*(2+x)*(1+2*x)/(1-8*x^2+x^4).
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EXAMPLE
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13 = a(2) = sqrt((5*A077247(2)^2 + 7)/3) = sqrt((5*10^2 + 7)/3)= sqrt(169) = 13.
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MATHEMATICA
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CoefficientList[Series[(1 - x) (2 + x) (1 + 2 x)/(1 - 8 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 11 2014 *)
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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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