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A104681 Expansion of (1-x-2*x^2-2*x^3-9*x^4-9*x^5-6*x^6+6*x^7-x^8-x^9-2*x^13+2*x^12) / (-x^12-1+2*x^6). 1
-1, 1, 2, 2, 9, 9, 4, -4, 5, 5, 18, 18, 7, -7, 8, 8, 27, 27, 10, -10, 11, 11, 36, 36, 13, -13, 14, 14, 45, 45, 16, -16, 17, 17, 54, 54, 19, -19, 20, 20, 63, 63, 22, -22, 23, 23, 72, 72, 25, -25, 26, 26, 81, 81, 28, -28, 29, 29, 90, 90, 31, -31, 32, 32, 99, 99, 34, -34, 35, 35, 108, 108, 37, -37, 38, 38, 117, 117, 40, -40, 41, 41, 126 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,2,0,0,0,0,0,-1).

FORMULA

For n>=0, a(6n+2)=a(6n+3)=6n+2; a(6n+5)=6n+5; a(6n+6)=-6n-6; a(6n+3)=a(6n+4)=9n+9.

a(n) = 2*a(n-6) - a(n-12) for n>13. - Colin Barker, May 14 2019

PROG

Floretion Algebra Multiplication Program, FAMP Code: 4kbasesigcycrokseq[ + .25'j - .25'k + .25j' - .25k' + .5'ii' + .25'ij' + .25'ik' + .25'ji' + .25'ki' + .5e]. See link to "Sequences in Context" for details on the "roktype" used.

(PARI) -Vec((1 - x - 2*x^2 - 2*x^3 - 9*x^4 - 9*x^5 - 6*x^6 + 6*x^7 - x^8 - x^9 + 2*x^12 - 2*x^13) / ((1 - x)^2*(1 + x)^2*(1 - x + x^2)^2*(1 + x + x^2)^2) + O(x^65)) \\ Colin Barker, May 14 2019

CROSSREFS

Sequence in context: A198423 A229116 A203904 * A056856 A133920 A229594

Adjacent sequences:  A104678 A104679 A104680 * A104682 A104683 A104684

KEYWORD

sign

AUTHOR

Creighton Dement, Apr 22 2005

STATUS

approved

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Last modified August 18 10:55 EDT 2019. Contains 326078 sequences. (Running on oeis4.)