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A047288
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Numbers that are congruent to {4, 6} mod 7.
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5
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4, 6, 11, 13, 18, 20, 25, 27, 32, 34, 39, 41, 46, 48, 53, 55, 60, 62, 67, 69, 74, 76, 81, 83, 88, 90, 95, 97, 102, 104, 109, 111, 116, 118, 123, 125, 130, 132, 137, 139, 144, 146, 151, 153, 158, 160, 165, 167, 172
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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) = a(n-1) + a(n-2) - a(n-3).
G.f.: x*(4 + 2*x + x^2)/((1-x)^2*(1+x)). (End)
a(n) = (-1 - 3*(-1)^n + 14*n)/4. - Colin Barker, May 14 2012
E.g.f.: 1 + ((14*x - 1)*exp(x) - 3*exp(-x))/4. - David Lovler, Sep 15 2022
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MATHEMATICA
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LinearRecurrence[{1, 1, -1}, {4, 6, 11}, 50] (* Harvey P. Dale, Jan 18 2013 *)
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PROG
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(PARI) a(n) = (-1 - 3*(-1)^n + 14*n)/4 \\ David Lovler, Sep 15 2022
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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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