<p>Recently we have presented some sufficient conditions so that the real sequence <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <msup> <mrow> <mo maxsize="2.4ex" minsize="2.4ex" stretchy="true">(</mo> <mn>1</mn> <mo>+</mo> <mfrac> <mi>α</mi> <mi>n</mi> </mfrac> <mo maxsize="2.4ex" minsize="2.4ex" stretchy="true">)</mo> </mrow> <mrow> <mi>n</mi> <mo>+</mo> <mi>p</mi> </mrow> </msup> </math></EquationSource> <EquationSource Format="TEX">$\big (1+\frac{\alpha }{n}\big )^{n+p}$</EquationSource> </InlineEquation>, <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <mi>n</mi> <mo>∈</mo> <mi mathvariant="double-struck">N</mi> </math></EquationSource> <EquationSource Format="TEX">$n\in {\mathbb{N}}$</EquationSource> </InlineEquation>, strictly increasingly converges to <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <msup> <mi>e</mi> <mi>α</mi> </msup> </math></EquationSource> <EquationSource Format="TEX">$e^{\alpha }$</EquationSource> </InlineEquation>, when <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mn>0</mn> <mo>≤</mo> <mn>2</mn> <mi>p</mi> <mo>&lt;</mo> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$0\le 2p&lt;\alpha $</EquationSource> </InlineEquation>, and shown that the sequence is strictly decreasing if and only if <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <mn>0</mn> <mo>&lt;</mo> <mi>α</mi> <mo>≤</mo> <mn>2</mn> <mi>p</mi> </math></EquationSource> <EquationSource Format="TEX">$0&lt;\alpha \le 2p$</EquationSource> </InlineEquation>. Here, we give a complete characterization of the monotonicity character of the sequence in the case <InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math> <mn>0</mn> <mo>≤</mo> <mn>2</mn> <mi>p</mi> <mo>&lt;</mo> <mi>α</mi> </math></EquationSource> <EquationSource Format="TEX">$0\le 2p&lt;\alpha $</EquationSource> </InlineEquation>, solving the most difficult case and the problem on the monotonicity character completely. To do this, among other things, we use several interesting new analytic inequalities.</p>

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Solution to the monotonicity problem of an interesting class of sequences of real numbers

  • Stevo Stević

摘要

Recently we have presented some sufficient conditions so that the real sequence ( 1 + α n ) n + p $\big (1+\frac{\alpha }{n}\big )^{n+p}$ , n N $n\in {\mathbb{N}}$ , strictly increasingly converges to e α $e^{\alpha }$ , when 0 2 p < α $0\le 2p<\alpha $ , and shown that the sequence is strictly decreasing if and only if 0 < α 2 p $0<\alpha \le 2p$ . Here, we give a complete characterization of the monotonicity character of the sequence in the case 0 2 p < α $0\le 2p<\alpha $ , solving the most difficult case and the problem on the monotonicity character completely. To do this, among other things, we use several interesting new analytic inequalities.