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A340134
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a(n+1) = a(n-2*a(n)) + 1, starting with a(1) = a(2) = 0.
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3
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0, 0, 1, 1, 1, 2, 1, 2, 2, 2, 3, 2, 3, 2, 3, 3, 3, 4, 3, 4, 3, 4, 3, 4, 4, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 5, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 6, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 7, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 8, 8, 9, 8, 9, 8, 9
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OFFSET
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1,6
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LINKS
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FORMULA
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a(n) = floor(sqrt(n-1)) + ((-1)^(n+floor(sqrt(n)))-1)/2.
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EXAMPLE
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a(3) = a(2-2*a(2))+1 = a(2)+1 = 1.
a(4) = a(3-2*a(3))+1 = a(1)+1 = 1.
a(5) = a(4-2*a(4))+1 = a(2)+1 = 1.
a(6) = a(5-2*a(5))+1 = a(3)+1 = 2.
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MATHEMATICA
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Table[Floor[Sqrt[n-1]] + ((-1)^(n+Floor[Sqrt[n]])-1)/2, {n, 87}] (* Stefano Spezia, Dec 29 2020 *)
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PROG
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(Python)
a = [0, 0]
for n in range(1, 1000):
a.append(a[n-2*a[n]]+1)
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CROSSREFS
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For a(n+1) = a(n-a(n)) + 1, starting with a(1) = 0, see A003056.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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