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Search: id:A137778
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| A137778 |
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Triangular sequence from coefficients of an expansion of a Rankine-Hugoniot relation function for density in terms of thermodynamic gamma as t and pressure ratio as x: p(x,t)=((t + 1)/(t - 1) + x)/(1 + (t + 1)*x/(t - 1)). |
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+0 1
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| -1, -2, -2, -4, -8, -4, -12, -36, -36, -12, -48, -192, -288, -192, -48, -240, -1200, -2400, -2400, -1200, -240, -1440, -8640, -21600, -28800, -21600, -8640, -1440, -10080, -70560, -211680, -352800, -352800, -211680, -70560, -10080, -80640, -645120, -2257920, -4515840, -5644800, -4515840
(list; table; graph; listen)
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OFFSET
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1,2
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COMMENT
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Row sums = A032184.
But for an odd function of 2^n this might be a simple:
p[x,n]= -f(2^n)*((x+1)/(x-1))^n/n!;
The importance of these density curves is
that they are related to Mach's numbers for
velocity in a medium.
It also seems important that the equation has a Moebius form that is
Blaschke/ Elliptic in shape in terms of gamma and pressure ratio pr:
F(pr)=(f(gamma)+pr)/(1+f(gamma)*pr).
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REFERENCES
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A. M. Kuethe, J.D. Schetzer,Foundations of Aerodynamics, John Wiley and sons, Inc. New York,1959, page 180
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FORMULA
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p(x,t)=((t + 1)/(t - 1) + x)/(1 + (t + 1)*x/(t -1))=Sum(Q(x,n)*t^n/n!,{n,0,Infinity}]; out_n,m]=n!*(1 - x)^(n))*Coefficient(Q(x,n).
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EXAMPLE
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{-1},
{-2, -2},
{-4, -8, -4},
{-12, -36, -36, -12},
{-48, -192, -288, -192, -48},
{-240, -1200, -2400, -2400, -1200, -240},
{-1440, -8640, -21600, -28800, -21600, -8640, -1440},
{-10080, -70560, -211680, -352800, -352800, -211680, -70560, -10080},
{-80640, -645120, -2257920, -4515840, -5644800, -4515840, -2257920, -645120, -80640},
{-725760, -6531840, -26127360, -60963840, -91445760, -91445760, -60963840, -26127360, -6531840, -725760},
{-7257600, -72576000, -326592000, -870912000, -1524096000, -1828915200, -1524096000, -870912000, -326592000, -72576000, -7257600}
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MATHEMATICA
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p[t_] = ((t + 1)/(t - 1) + x)/(1 + (t + 1)*x/(t - 1)); Table[ExpandAll[ FullSimplify[(n!*(1 - x)^(n))*SeriesCoefficient[ Series[p[t], {t, 0, 30}], n]]], {n, 0, 10}]; a = Table[ CoefficientList[ExpandAll[ FullSimplify[(n!*(1 - x)^(n))*SeriesCoefficient[Series[p[t], {t, 0, 30}], n]]], x], {n, 0, 10}]; Flatten[a] Table[ Apply[Plus, CoefficientList[ExpandAll[ FullSimplify[(n!*(1 - x)^(n))*SeriesCoefficient[Series[p[t], {t, 0, 30}], n]]], x]], {n, 0, 10}];
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CROSSREFS
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Cf. A007318, A032184.
Sequence in context: A121175 A038208 A116694 this_sequence A000017 A032522 A077964
Adjacent sequences: A137775 A137776 A137777 this_sequence A137779 A137780 A137781
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KEYWORD
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tabl,uned,sign
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Apr 28 2008
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