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A271893
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Expansion of (2*x+1)*(1-x) / ( 1-2*x-4*x^2+6*x^3 ).
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1
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1, 3, 8, 22, 58, 156, 412, 1100, 2912, 7752, 20552, 54640, 144976, 385200, 1022464, 2715872, 7210400, 19149504, 50845376, 135026368, 358537216, 952107648, 2528205952, 6713619200, 17827416320, 47340073728, 125708097536, 333811992064, 886415931904, 2353831246848, 6250454268928, 16597737933824
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OFFSET
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0,2
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COMMENTS
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Sum of all first elements at level n of the TRIP-Stern sequence corresponding to the permutation triple (e,13,23)
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LINKS
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Ilya Amburg, Krishna Dasaratha, Laure Flapan, Thomas Garrity, Chansoo Lee, Cornelia Mihaila, Nicholas Neumann-Chun, Sarah Peluse, Matthew Stoffregen, Stern Sequences for a Family of Multidimensional Continued Fractions: TRIP-Stern Sequences, arXiv:1509.05239 [math.CO], 2015, Section 7.2.1
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FORMULA
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a(n) >= 2^n.
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PROG
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(PARI) x='x+O('x^99); Vec((2*x+1)*(1-x)/(1-2*x-4*x^2+6*x^3)) \\ Altug Alkan, Apr 16 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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