A249403 Decimal expansion of the maximum M(7) of the ratio (Sum_{k=1..7} (x(1)*x(2)*...*x(k))^(1/k))/(x(1) + ... + x(7)) taken over x(1), ..., x(7) > 0.

1, 5, 8, 0, 0, 3, 7, 2, 1, 0, 6, 3, 2, 0, 5, 2, 3, 5, 2, 0, 8, 4, 0, 6, 3, 4, 9, 8, 1, 8, 3, 2, 6, 4, 4, 9, 2, 1, 1, 2, 8, 1, 5, 8, 0, 5, 9, 1, 6, 5, 9, 6, 1, 9, 7, 0, 1, 7, 4, 2, 3, 6, 9, 2, 0, 6, 0, 1, 5, 3, 7, 3, 7, 1, 0, 5, 3, 7, 7, 1, 1, 3, 5, 9, 2, 3, 5, 6, 4, 8, 0, 9, 0, 2, 1, 7, 0, 1, 4, 4, 8, 7, 0, 9, 0

Offset

1,2

Comments

M(2) = (1+sqrt(2))/2, M(3) = 4/3.

M(n) = exp(1) - 2*Pi^2*exp(1)/(log(n))^2 + O(1/(log(n))^3), [de Bruijn, 1963].

References

N. G. de Bruijn, Carleman's inequality for finite series, Nederl. Akad. Wetensch. Proc. Ser. A 66 = Indag, Math., 25:505-514, 1963.

R. Witula, D. Jama, D. Slota, E. Hetmaniok, Finite version of Carleman's and Knopp's inequalities, Zeszyty naukowe Politechniki Slaskiej (Gliwice, Poland) 92 (2010), 93-96.

Links

Table of n, a(n) for n=1..105.

Steven R. Finch, Carleman's inequality, 2013. [Cached copy, with permission of the author]

Yu-Dong Wu, Zhi-Hua Zhang and Zhi-Gang Wang, The Best Constant for Carleman's Inequality of Finite Type, Acta Mathematica Academiae Paedagogicae Nyiregyhaziensis, Vol. 24, No. 2, 2008.

Example

1.5800372106320523520840634981832644921128158059165961970174236920601537371...

Mathematica

RealDigits[c7/.FindRoot[{1 + x2/2 + x3/3 + x4/4 + x5/5 + x6/6 + x7/7 == c7, x2/2 + x3/3 + x4/4 + x5/5 + x6/6 + x7/7 == c7*x2^2, x3/3 + x4/4 + x5/5 + x6/6 + x7/7 == c7*x3^3/x2^2, x4/4 + x5/5 + x6/6 + x7/7 == c7*x4^4/x3^3, x5/5 + x6/6 + x7/7 == c7*x5^5/x4^4, x6/6 + x7/7 == c7*x6^6/x5^5, x7/7 == c7*x7^7/x6^6}, {{c7, 3/2}, {x2, 1/2}, {x3, 1/2}, {x4, 1/2}, {x5, 1/2}, {x6, 1/2}, {x7, 1/2}}, WorkingPrecision->120], 10, 105][[1]]

Crossrefs

Cf. A174968 = M(2), A219245 = M(4), A219246 = M(5), A219336 = M(6).

Sequence in context: A090817 A357054 A198875 * A201756 A242674 A154052

Adjacent sequences: A249400 A249401 A249402 * A249404 A249405 A249406

Keyword

nonn,cons

Author

Vaclav Kotesovec, Oct 27 2014

Status

approved