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A037761
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Base-7 digits are, in order, the first n terms of the periodic sequence with initial period 3,0,1,2.
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2
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3, 21, 148, 1038, 7269, 50883, 356182, 2493276, 17452935, 122170545, 855193816, 5986356714, 41904497001, 293331479007, 2053320353050, 14373242471352, 100612697299467, 704288881096269, 4930022167673884
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = (-100-25*(-1)^n-(24-i*32)*(-i)^n-(24+32*i)*i^n+173*7^n)/400, where i=sqrt(-1).
a(n) = 7*a(n-1)+a(n-4)-7*a(n-5).
G.f.: x*(2*x^3+x^2+3) / ((x-1)*(x+1)*(7*x-1)*(x^2+1)). (End)
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MATHEMATICA
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CoefficientList[Series[(2 x^3 + x^2 + 3)/((x - 1) (x + 1) (7 x - 1) (x^2 + 1)), {x, 0, 30}], x] (* Vincenzo Librandi, May 01 2014 *)
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PROG
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(PARI) Vec(x*(2*x^3+x^2+3)/((x-1)*(x+1)*(7*x-1)*(x^2+1)) + O(x^100)) \\ Colin Barker, Apr 30 2014
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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