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A047279
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Numbers that are congruent to {0, 1, 2, 6} mod 7.
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1
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0, 1, 2, 6, 7, 8, 9, 13, 14, 15, 16, 20, 21, 22, 23, 27, 28, 29, 30, 34, 35, 36, 37, 41, 42, 43, 44, 48, 49, 50, 51, 55, 56, 57, 58, 62, 63, 64, 65, 69, 70, 71, 72, 76, 77, 78, 79, 83, 84, 85, 86, 90, 91, 92, 93, 97, 98, 99, 100, 104, 105, 106, 107, 111, 112
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OFFSET
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1,3
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LINKS
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FORMULA
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G.f.: x^2*(1+x+4*x^2+x^3) / ( (1+x)*(1+x^2)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011
a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
a(n) = (14n-17+3*(i^(2n)+(1+i)*i^(-n)+(1-i)*i^n))/8 where i = sqrt(-1).
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MAPLE
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MATHEMATICA
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LinearRecurrence[{1, 0, 0, 1, -1}, {0, 1, 2, 6, 7}, 80] (* Harvey P. Dale, Jun 15 2015 *)
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PROG
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(Magma) [n : n in [0..100] | n mod 7 in [0, 1, 2, 6]]; // Wesley Ivan Hurt, May 21 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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EXTENSIONS
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STATUS
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approved
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