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 A109731 a(n) = - 4*a(n-2) - a(n-4), a(0) = 1, a(1) = -4, a(2) = -6, a(3) = 15. 0
 1, -4, -6, 15, 23, -56, -86, 209, 321, -780, -1198, 2911, 4471, -10864, -16686, 40545, 62273, -151316, -232406, 564719, 867351, -2107560, -3236998, 7865521, 12080641, -29354524, -45085566, 109552575, 168261623, -408855776 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Sequence A002530 and A002531 are also generated by the floretion given in the program code. LINKS Robert Munafo, Sequences Related to Floretions Index entries for linear recurrences with constant coefficients, signature (0, -4, 0, -1). FORMULA a(2n) = ((-1)^n)*A054491(n), a(2n+1) = ((-1)^n+1)*A001353(n+1). G.f. (1-4*x-2*x^2-x^3)/(x^4+4*x^2+1) MAPLE Floretion Algebra Multiplication Program, FAMP Code: 1lestesseq[A*B] with A = + .25'i + .25i' + 'ij' + .25'jk' + .25'kj' and B = + j' + k' + 'ii'. MATHEMATICA LinearRecurrence[{0, -4, 0, -1}, {1, -4, -6, 15}, 40] (* Harvey P. Dale, Mar 05 2013 *) CROSSREFS Cf. A054491, A001353, A002530. Sequence in context: A119034 A100911 A034765 * A027631 A128620 A045907 Adjacent sequences:  A109728 A109729 A109730 * A109732 A109733 A109734 KEYWORD easy,sign AUTHOR Creighton Dement, Aug 09 2005 STATUS approved

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