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A085455 Sum(Sum a(j)a(i-j),(j=0,..,i)),(i=0,..,n)=(-3)^n. 2
1, -2, 4, -10, 26, -70, 192, -534, 1500, -4246, 12092, -34606, 99442, -286730, 829168, -2403834, 6984234, -20331558, 59287740, -173149662, 506376222, -1482730098, 4346486256, -12754363650, 37461564504, -110125172682, 323990062452, -953883382354, 2810310510110, -8284915984726 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..29.

FORMULA

G.f.: A(x)=Sqrt((1-x)/(1+3x))

G.f.: G(0), where G(k)= 1 + 4*x*(4*k+1)/( (x-1)*(4*k+2) - x*(x-1)*(4*k+2)*(4*k+3)/(x*(4*k+3) + (x-1)*(k+1)/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 26 2013

MATHEMATICA

CoefficientList[Series[Sqrt[(1-x)/(1+3x)], {x, 0, 30}], x]

CROSSREFS

Absolute values are in A025565.

Sequence in context: A084575 A081881 A025565 * A055226 A097085 A071962

Adjacent sequences:  A085452 A085453 A085454 * A085456 A085457 A085458

KEYWORD

easy,sign

AUTHOR

Mario Catalani (mario.catalani(AT)unito.it), Jul 01 2003

STATUS

approved

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Last modified April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)