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A225813
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a(n) = (10^n)^2 + 7(10^n) + 1.
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1
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9, 171, 10701, 1007001, 100070001, 10000700001, 1000007000001, 100000070000001, 10000000700000001, 1000000007000000001, 100000000070000000001, 10000000000700000000001, 1000000000007000000000001, 100000000000070000000000001, 10000000000000700000000000001
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = 111*a(n-1)-1110*a(n-2)+1000*a(n-3). - Colin Barker, Apr 27 2015
G.f.: -9*(190*x^2-92*x+1) / ((x-1)*(10*x-1)*(100*x-1)). - Colin Barker, Apr 27 2015
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MAPLE
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MATHEMATICA
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Table[(10^n)^2 + 7*(10^n) + 1, {n, 0, 20}] (* T. D. Noe, Aug 12 2013 *)
LinearRecurrence[{111, -1110, 1000}, {9, 171, 10701}, 20] (* Harvey P. Dale, Apr 12 2020 *)
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PROG
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(PARI) Vec(-9*(190*x^2-92*x+1)/((x-1)*(10*x-1)*(100*x-1)) + O(x^100)) \\ Colin Barker, Apr 27 2015
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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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