A109731 - OEIS

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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.

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; 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`
	FORMULA	`a(2n) = ((-1)^n)A054491(n), a(2n+1) = ((-1)^n+1)A001353(n+1). G.f. (1-4x-2x^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'.`
	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 (creighton.k.dement(AT)uni-oldenburg.de), Aug 09 2005`

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.