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A081680
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A sum of decreasing powers.
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2
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1, 2, 4, 23, 274, 2927, 27094, 228923, 1827634, 14069687, 105715534, 781107923, 5702856394, 41273440847, 296753044774, 2122921300523, 15127554995554, 107462125890407, 761485887090814, 5385095865086723, 38019827430709114
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n)=(7^n-6^n-5^n-4^n+4*3^n)/2.
G.f.: -(1083*x^4-762*x^3+199*x^2-23*x+1)/((3*x-1)*(4*x-1)*(5*x-1)*(6*x-1)*(7*x-1)). [Colin Barker, Sep 07 2012]
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MATHEMATICA
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LinearRecurrence[{25, -245, 1175, -2754, 2520}, {1, 2, 4, 23, 274}, 30] (* Harvey P. Dale, Feb 19 2018 *)
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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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