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A047389
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Numbers that are congruent to {3, 5} mod 7.
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6
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3, 5, 10, 12, 17, 19, 24, 26, 31, 33, 38, 40, 45, 47, 52, 54, 59, 61, 66, 68, 73, 75, 80, 82, 87, 89, 94, 96, 101, 103, 108, 110, 115, 117, 122, 124, 129, 131, 136, 138, 143, 145, 150, 152, 157, 159, 164, 166, 171
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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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G.f.: x*(3 + 2*x + 2*x^2)/((1+x)*(1-x)^2).
a(n) - a(n-1) - a(n-2) + a(n-3) = 0 for n > 3.
a(n) = (14*n - 5 - 3*(-1)^n)/4. (End)
E.g.f.: 2 + ((14*x - 5)*exp(x) - 3*exp(-x))/4. - David Lovler, Sep 13 2022
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MATHEMATICA
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#+{3, 5}&/@(7*Range[0, 30])//Flatten (* Harvey P. Dale, Oct 10 2019 *)
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PROG
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(PARI) a(n) = (14*n - 5 - 3*(-1)^n)/4 \\ David Lovler, Sep 13 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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