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A114014 A series expansion of a quadric Jasinski rational polynomial based on A112627 that is Farey like in p[1/2]=1. +0
1
1, 7, 33, 127, 529, 2031, 8465, 32495, 135441, 519919, 2167057, 8318703, 34672913, 133099247, 554766609, 2129587951, 8876265745, 34073407215, 142020251921, 545174515439, 2272324030737, 8722792247023, 36357184491793 (list; graph; listen)
OFFSET

0,2

COMMENT

if p[x]=k*Product[(x-a(i),{i,1,n}]/Product[(x-b(i),{i,1,n}] and a(i), b(i) and k are real and rational, then p[x] will be rational. If you keep the roots out of the interior of the interval (0,1), then Farey function on that interval will be relatively smooth as well. In this case the 1/4 root makes that impossible but adding an x for a zero roots ties down the zero end and the other end is at 2.

FORMULA

b(n) = coefficients of (9/64)*(x + 1/2)^4/(x*(x - 1/4)*(x + 1/4)*(x + 1)); a(n) = 2*a(n-1) + 3; generating function = 1/(exp(x)-1).

MATHEMATICA

b = Delete[ -(64/9)*ReplacePart[Table[Coefficient[Series[(9/64)*(x + 1/2)^4/((x - 1/4)*(x + 1/4)*(x + 1)), {x, 0, 30}], x^n], {n, -1, 30}], -9/64, 2], 1]

CROSSREFS

Cf. A112627.

Sequence in context: A131211 A100855 A000605 this_sequence A066810 A034577 A141291

Adjacent sequences: A114011 A114012 A114013 this_sequence A114015 A114016 A114017

KEYWORD

nonn,uned

AUTHOR

Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jan 31 2006

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.


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