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A277937
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Number of runs of 1's of length 1 in the binary expansion of n.
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1
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0, 1, 1, 0, 1, 2, 0, 0, 1, 2, 2, 1, 0, 1, 0, 0, 1, 2, 2, 1, 2, 3, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 2, 2, 1, 2, 3, 1, 1, 2, 3, 3, 2, 1, 2, 1, 1, 0, 1, 1, 0, 1, 2, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 2, 2, 1, 2, 3, 1, 1, 2, 3, 3, 2, 1, 2, 1, 1, 2, 3, 3, 2, 3, 4, 2
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OFFSET
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0,6
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COMMENTS
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2^a(n) is the run length transform of 1,2,1,1,1,1,....
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LINKS
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FORMULA
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a(2n) = a(n), a(4n+1) = a(8n+1) = a(n) + 1, a(8n+3) = a(n), a(8n+5) = a(2n+1) + 1, a(8n+7) = a(4n+3).
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EXAMPLE
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a(25) = 1 since 25 = 11001_2 has one runs of 1's of length 1.
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PROG
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(Python)
return sum(1 for d in bin(n)[2:].split('0') if len(d) == 1)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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