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A125691
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Expansion of 1/(1 - x - 3x^2 + x^3).
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5
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1, 1, 4, 6, 17, 31, 76, 152, 349, 729, 1624, 3462, 7605, 16367, 35720, 77216, 168009, 363937, 790748, 1714550, 3722857, 8075759, 17529780, 38034200, 82547781, 179120601, 388729744, 843543766, 1830612397, 3972513951, 8620807376, 18707736832, 40597645009, 88100048129
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OFFSET
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0,3
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COMMENTS
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Antidiagonal sums of number triangle A125690.
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LINKS
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MATHEMATICA
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CoefficientList[Series[1/(1 - x - 3x^2 + x^3), {x, 0, 28}], x] (* Indranil Ghosh, Mar 10 2017 *)
LinearRecurrence[{1, 3, -1}, {1, 1, 4}, 40] (* Harvey P. Dale, Jul 13 2019 *)
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PROG
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(PARI) Vec(1/(1 - x - 3*x^2 + x^3) + O(x^29)) \\ Indranil Ghosh, Mar 10 2017
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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