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A107585
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a(n) = 5^n - 5*n.
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10
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1, 0, 15, 110, 605, 3100, 15595, 78090, 390585, 1953080, 9765575, 48828070, 244140565, 1220703060, 6103515555, 30517578050, 152587890545, 762939453040, 3814697265535, 19073486328030, 95367431640525, 476837158203020, 2384185791015515, 11920928955078010, 59604644775390505, 298023223876953000
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OFFSET
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0,3
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COMMENTS
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Numbers a(n)=k such that the number m with n 5's and k 1's has digit product = digit sum = 5^n.
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LINKS
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FORMULA
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G.f.: ( -1-26*x^2+7*x ) / ( (5*x-1)*(x-1)^2 ). - R. J. Mathar, Oct 26 2011
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EXAMPLE
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Corresponding numbers m are 1, 5, 11111111111111155, ...
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MATHEMATICA
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Table[5^m-5*m, {m, 0, 10}]
LinearRecurrence[{7, -11, 5}, {1, 0, 15}, 30] (* Harvey P. Dale, Oct 21 2015 *)
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PROG
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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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EXTENSIONS
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STATUS
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approved
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