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A123148 Triangle read by rows: T(n,k) is the coefficient of x^k in the polynomial p[n,x] defined by p[0,x]=-1, p[1,x]=x-2, p[n,x]=-xp[n-1,x]+2p[n-2,x] for n>=3 (0<=k<=n). 0
-1, -2, 1, -2, 2, -1, -4, 4, -2, 1, -4, 8, -6, 2, -1, -8, 12, -12, 8, -2, 1, -8, 24, -24, 16, -10, 2, -1, -16, 32, -48, 40, -20, 12, -2, 1, -16, 64, -80, 80, -60, 24, -14, 2, -1, -32, 80, -160, 160, -120, 84, -28, 16, -2, 1, -32, 160, -240, 320, -280, 168, -112, 32, -18, 2, -1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums yield -1,-1,-1,... . Alternating row sums yield the Jacobsthal sequence (A001045) with changed signs.

LINKS

Table of n, a(n) for n=0..65.

EXAMPLE

-1

-2+x

-2+2*x-x^2

-4+4*x-2*x^2+x^3

-4+8*x-6*x^2+2*x^3-x^4

MAPLE

p[0]:=-1: p[1]:=x-2: for n from 2 to 10 do p[n]:=sort(expand(-x*p[n-1]+2*p[n-2])) od: for n from 0 to 10 do seq(coeff(p[n], x, k), k=0..n) od; # yields sequence in triangular form

MATHEMATICA

a = -1; b = 2; p[0, x] = -1; p[1, x] = x - 2; p[k_, x_] := p[k, x] = a*x*p[k - 1, x] + b*p[k - 2, x] w = Table[CoefficientList[p[n, x], x], {n, 0, 10}]; Flatten[w]

CROSSREFS

Sequence in context: A035369 A129719 A062602 * A173410 A166548 A273138

Adjacent sequences:  A123145 A123146 A123147 * A123149 A123150 A123151

KEYWORD

sign,tabl

AUTHOR

Roger L. Bagula, Oct 01 2006

EXTENSIONS

Edited by N. J. A. Sloane, Oct 29 2006

STATUS

approved

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Last modified June 20 06:56 EDT 2021. Contains 345157 sequences. (Running on oeis4.)