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A166117
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a(0)=0, a(1)=1, a(2)=2 and a(n) = a(n-1) - 2a(n-2) + a(n-3).
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1
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0, 1, 2, 0, -3, -1, 5, 4, -7, -10, 8, 21, -5, -39, -8, 65, 42, -96, -115, 119, 253, -100, -487, -34, 840, 421, -1293, -1295, 1712, 3009, -1710, -6016, 413, 10735, 3893, -17164, -14215, 24006, 35272, -26955, -73493, 15689, 135720, 30849, -224902
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = n for n<3, else a(n) = a(n-1) - 2*a(n-2) + a(n-3).
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EXAMPLE
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a(0)=0, a(1)=1, a(2)=2, a(3) = 2-2(1)+0 = 0, a(4)= 0-2(2)+ 1 = -3, a(5) = -3 -2(0) + 2 = -1, a(6)= -1 -2(-3)+ 0 = 5.
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MAPLE
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a:= proc(n) a(n):=`if`(n<3, n, a(n-1)-2*a(n-2)+a(n-3)) end:
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MATHEMATICA
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LinearRecurrence[{1, -2, 1}, {0, 1, 2}, 10] (* G. C. Greubel, Apr 26 2016 *)
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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Barry Wells (wells.barry(AT)gmail.com), Oct 06 2009
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STATUS
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approved
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