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Search: id:A078039
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| A078039 |
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Expansion of (1-x)/(1+x-2*x^2+x^3). |
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+0
7
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| 1, -2, 4, -9, 19, -41, 88, -189, 406, -872, 1873, -4023, 8641, -18560, 39865, -85626, 183916, -395033, 848491, -1822473, 3914488, -8407925, 18059374, -38789712, 83316385, -178955183, 384377665, -825604416, 1773314929, -3808901426, 8181135700, -17572253481, 37743426307, -81069068969
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Comment from wouter.meeussen(AT)pandora.be, Mar 06 2004: the repeated substitution 0 -> {0,1,2}, 1 -> {0,1,2,3}, 2 -> {0,1}, 3 -> {0,1,2}, starting on list {0} and flattening at each step { {sequence1}, {sequence2},..} to {sequence1,sequence2,..} generates a list after n steps with length =a(n)=A078039.
Sequence is identical to its second differences negated, minus the first 3 terms. - Paul Curtz (bpcrtz(AT)free.fr), Feb 10 2008
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FORMULA
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a(n)=-a(n-1)+2a(n-2)-a(n-3). - Paul Curtz (bpcrtz(AT)free.fr), Feb 10 2008
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CROSSREFS
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Cf. A002478.
Sequence in context: A142474 A141015 A141683 this_sequence A036622 A001384 A089941
Adjacent sequences: A078036 A078037 A078038 this_sequence A078040 A078041 A078042
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KEYWORD
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sign
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Nov 17 2002
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