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 A158499 Expansion of (1+sqrt(1-4x))/(2-4x). 1
 1, 1, 1, 0, -5, -24, -90, -312, -1053, -3536, -11934, -40664, -140114, -488240, -1719380, -6113200, -21921245, -79200160, -288045110, -1053728920, -3874721030, -14313562480, -53093391980, -197669347600, -738398308850, -2766700765024 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Hankel transform is A056594 with g.f. 1/(1+x^2). Row sums of the Riordan array (sqrt(1-4x)/(1-2x),xc(x)^2), c(x) the g.f. of A000108. The inverse Catalan transform yields A146559. - R. J. Mathar, Mar 20 2009 LINKS Matthew House, Table of n, a(n) for n = 0..1669 Paul Barry, On a Central Transform of Integer Sequences, arXiv:2004.04577 [math.CO], 2020. FORMULA a(n) = Sum_{k=0..n} binomial(2k,k)*A158495(n-k). Conjecture: n*a(n) +6*(1-n)*a(n-1) +4*(2*n-3)*a(n-2)=0. - R. J. Mathar, Nov 14 2011 This conjecture has been proven. - Matthew House, Nov 08 2015 MATHEMATICA CoefficientList[ Series[(1 + Sqrt[1 - 4x])/(2 - 4x), {x, 0, 26}], x] (* Robert G. Wilson v, Nov 08 2015 *) PROG (PARI) x='x+O('x^33); Vec(((1-4*x)+sqrt(1-4*x))/(2*(1-2*x)*sqrt(1-4*x))) \\ Altug Alkan, Nov 08 2015 CROSSREFS Sequence in context: A089095 A220316 A220339 * A074085 A145914 A066316 Adjacent sequences: A158496 A158497 A158498 * A158500 A158501 A158502 KEYWORD easy,sign AUTHOR Paul Barry, Mar 20 2009 EXTENSIONS Name edited by Matthew House, Nov 08 2015 STATUS approved

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Last modified June 21 23:34 EDT 2024. Contains 373560 sequences. (Running on oeis4.)