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A077237
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Combined Diophantine Chebyshev sequences A054491 and A077234.
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3
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1, 2, 6, 9, 23, 34, 86, 127, 321, 474, 1198, 1769, 4471, 6602, 16686, 24639, 62273, 91954, 232406, 343177, 867351, 1280754, 3236998, 4779839, 12080641, 17838602, 45085566, 66574569, 168261623
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OFFSET
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0,2
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COMMENTS
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-3*a(n)^2 + b(n)^2 = 13, with the companion sequence b(n)= A077238(n).
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LINKS
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FORMULA
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G.f.: (1+x)*(1+x+x^2)/(1-4*x^2+x^4).
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EXAMPLE
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3*a(2)^2 + 13 = 3*36+13 = 121 = 11^2 = A077238(2)^2.
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MATHEMATICA
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CoefficientList[Series[(1 + x) (1 + x + x^2)/(1 - 4 x^2 + x^4), {x, 0, 28}], x] (* Michael De Vlieger, Feb 11 2017 *)
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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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