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A178710
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Partial sums of floor(4^n/7).
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1
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0, 2, 11, 47, 193, 778, 3118, 12480, 49929, 199725, 798911, 3195656, 12782636, 51130558, 204522247, 818089003, 3272356029, 13089424134, 52357696554, 209430786236, 837723144965, 3350892579881, 13403570319547, 53614281278212, 214457125112872
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = round((8*4^n - 14*n - 13)/42).
a(n) = floor((8*4^n - 14*n - 8)/42).
a(n) = ceiling((8*4^n - 14*n - 18)/42).
a(n) = round((8*4^n - 14*n - 8)/42).
a(n) = a(n-3) + 3*4^(n-2) - 1, n > 3.
a(n) = 5*a(n-1) - 4*a(n-2) + a(n-3) - 5*a(n-4) + 4*a(n-5), n > 5.
G.f.: x^2*(2+x)/ ( (1-4*x)*(1+x+x^2)*(1-x)^2 ).
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EXAMPLE
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a(4) = 0 + 2 + 9 + 36 = 47.
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MAPLE
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A178710 := proc(n) add( floor(4^i/7), i=0..n) ; end proc:
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MATHEMATICA
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Accumulate[Floor[4^Range[30]/7]] (* or *) LinearRecurrence[{5, -4, 1, -5, 4}, {0, 2, 11, 47, 193}, 30] (* Harvey P. Dale, Aug 15 2015 *)
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PROG
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(PARI) vector(30, n, ((8*4^n-14*n-8)/42)\1) \\ G. C. Greubel, Jan 25 2019
(Sage) [floor((8*4^n-14*n-8)/42) for n in (1..30)] # G. C. Greubel, Jan 25 2019
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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STATUS
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approved
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