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A047320
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Numbers that are congruent to {0, 5, 6} mod 7.
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1
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0, 5, 6, 7, 12, 13, 14, 19, 20, 21, 26, 27, 28, 33, 34, 35, 40, 41, 42, 47, 48, 49, 54, 55, 56, 61, 62, 63, 68, 69, 70, 75, 76, 77, 82, 83, 84, 89, 90, 91, 96, 97, 98, 103, 104, 105, 110, 111, 112, 117, 118, 119, 124, 125, 126, 131, 132, 133, 138, 139, 140
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: x^2*(5+x+x^2) / ((1+x+x^2)*(x-1)^2). - R. J. Mathar, Dec 03 2011
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
a(n) = (21*n-9-8*sqrt(3)*sin(2*n*Pi/3))/9.
a(3k) = 7k-1, a(3k-1) = 7k-2, a(3k-2) = 7k-7. (End)
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MAPLE
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MATHEMATICA
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Select[Range[0, 200], MemberQ[{0, 5, 6}, Mod[#, 7]]&] (* Harvey P. Dale, May 25 2012 *)
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PROG
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(Magma) [n : n in [0..150] | n mod 7 in [0, 5, 6]]; // Wesley Ivan Hurt, Jun 07 2016
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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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