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A047282
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Numbers that are congruent to {1, 3, 6} mod 7.
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2
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1, 3, 6, 8, 10, 13, 15, 17, 20, 22, 24, 27, 29, 31, 34, 36, 38, 41, 43, 45, 48, 50, 52, 55, 57, 59, 62, 64, 66, 69, 71, 73, 76, 78, 80, 83, 85, 87, 90, 92, 94, 97, 99, 101, 104, 106, 108, 111, 113, 115, 118, 120, 122, 125, 127, 129, 132, 134, 136, 139, 141
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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*(1+2*x+3*x^2+x^3)/((1+x+x^2)*(x-1)^2). - R. J. Mathar, Oct 25 2011
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
a(n) = (21*n-12+3*cos(2*n*Pi/3)+sqrt(3)*sin(2*n*Pi/3))/9.
a(3*k) = 7*k-1, a(3*k-1) = 7*k-4, a(3*k-2) = 7*k-6. (End)
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MAPLE
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MATHEMATICA
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Select[Range[0, 150], MemberQ[{1, 3, 6}, Mod[#, 7]] &] (* Wesley Ivan Hurt, Jun 10 2016 *)
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PROG
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(Magma) [n : n in [0..150] | n mod 7 in [1, 3, 6]]; // Wesley Ivan Hurt, Jun 10 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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