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A095768
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a(n) = 2^(n+1) - n.
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6
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3, 6, 13, 28, 59, 122, 249, 504, 1015, 2038, 4085, 8180, 16371, 32754, 65521, 131056, 262127, 524270, 1048557, 2097132, 4194283, 8388586, 16777193, 33554408, 67108839, 134217702, 268435429, 536870884, 1073741795, 2147483618
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OFFSET
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1,1
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COMMENTS
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Least k such that valuation(A004001(k),2) = n.
Apart from initial term, row sums of triangle A135087.
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LINKS
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FORMULA
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O.g.f.: -x(3-6x+4x^2)/((-1+x)^2*(-1+2x)).
a(n) = 4a(n-1) - 5a(n-2) + 2a(n-3). (End)
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MATHEMATICA
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LinearRecurrence[{4, -5, 2}, {3, 6, 13}, 40] (* Harvey P. Dale, Jan 02 2012 *)
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PROG
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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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