Table 1 Values of successive lower approximations ${\mathit{\alpha }}_{\mathit{n}}\mathbf{(}\mathit{k}\mathbf{)}$ and upper approximations ${\mathit{\beta }}_{\mathit{n}}\mathbf{(}\mathit{k}\mathbf{)}$ , $\mathit{n}\mathbf{=}\mathbf{0}\mathbf{,}\mathbf{1}\mathbf{,}\mathbf{2}\mathbf{,}\mathbf{3}\mathbf{,}\mathbf{4}\mathbf{,}\mathbf{5}\mathbf{,}\mathbf{6}$

${\beta }_0(k)$

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${\beta }_1(k)$

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${\beta }_2(k)$

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${\beta }_3(k)$

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${\beta }_4(k)$

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u(k)

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${\alpha }_6(k)$

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${\alpha }_5(k)$

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${\alpha }_4(k)$

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${\alpha }_3(k)$

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${\alpha }_2(k)$

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${\alpha }_1(k)$

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${\alpha }_0(k)$

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