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A155721
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Positions of parity change in A033035.
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0
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4, 20, 84, 340, 1364, 5460, 21844, 87380, 349524, 1398100, 5592404, 22369620, 89478484, 357913940, 1431655764, 5726623060, 22906492244, 91625968980, 366503875924, 1466015503700, 5864062014804, 23456248059220, 93824992236884
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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a(n=1,2..)=(4/3)*(4^n-1)=A080674(n).
a(n) = 5*a(n-1) - 4*a(n-2) for n > 2. G.f.: 4*x/((x - 1)*(4*x - 1)). - Chai Wah Wu, Aug 30 2019
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EXAMPLE
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A033035(n=1..4) all are odd, then A033035(n=5..20) all are even, then A033035(n=21..84) all are odd, then A033035(n=85..340) all are even, etc.
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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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