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 A096406 a(1) = 4; then alternately add -4 and multiply by -2. 0
 4, 0, 0, -4, 8, 4, -8, -12, 24, 20, -40, -44, 88, 84, -168, -172, 344, 340, -680, -684, 1368, 1364, -2728, -2732, 5464, 5460, -10920, -10924, 21848, 21844, -43688, -43692, 87384, 87380, -174760, -174764, 349528, 349524, -699048, -699052, 1398104, 1398100, -2796200, -2796204, 5592408, 5592404 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Applet randomly selects from among nine algorithms and each algorithm has its own random parameters. Six terms are presented and you get to guess the next term. LINKS Alexander Bogomolny's Cut-the-Knot.org, What's Next? Index entries for linear recurrences with constant coefficients, signature (0,-1,0,2). FORMULA a(1)=4, a(2n)=a(2n-1)-4, a(2n+1)=a(2n)*(-2). (1/3) [2 - 6(-1)^n - 2(-2)^ceiling(n/2) ]. - Ralf Stephan, Dec 04 2004 O.g.f.: 4*x*(-1-x^2+x^3)/((-1+x)*(1+x)*(1+2*x^2)). - R. J. Mathar, Dec 05 2007 a(1)=4, a(2)=0, a(3)=0, a(4)=-4, a(n)=-a(n-2)+2*a(n-4). - Harvey P. Dale, May 01 2016 MATHEMATICA LinearRecurrence[{0, -1, 0, 2}, {4, 0, 0, -4}, 50] (* Harvey P. Dale, May 01 2016 *) CROSSREFS Sequence in context: A204301 A204084 A096904 * A189885 A151673 A005397 Adjacent sequences:  A096403 A096404 A096405 * A096407 A096408 A096409 KEYWORD sign,easy AUTHOR Herman DeWeerd (bhdeweerd(AT)worldnet.att.net), Aug 07 2004 EXTENSIONS Description found by Ray Chandler, Aug 07 2004 STATUS approved

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Last modified October 17 14:25 EDT 2018. Contains 316281 sequences. (Running on oeis4.)