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Search: id:A135569
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| A135569 |
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a(n) = S2(n)*2^n; where S2(n) is digit sum of n, n in binary notation. |
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+0
1
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| 0, 2, 4, 16, 16, 64, 128, 384, 256, 1024, 2048, 6144, 8192, 24576, 49152, 131072, 65536, 262144, 524288, 1572864, 2097152, 6291456, 12582912, 33554432, 33554432, 100663296, 201326592, 536870912, 805306368, 2147483648, 4294967296
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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For all n we have : 2/n <= a(n+1)/a(n)<= 4. This holds because a(2^n -1)= n*2^(2^n -1); a(2^n)= 2^2^n; a(2^n +1)=4*2^2^n.
a(n)=A000120(n)*2^n. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 03 2008
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MAPLE
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A000120 := proc(n) add(i, i=convert(n, base, 2)) ; end: A135569 := proc(n) A000120(n)*2^n ; end: seq(A135569(n), n=0..80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 03 2008
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CROSSREFS
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Cf. A000120, A010060.
Sequence in context: A073923 A098819 A067846 this_sequence A131560 A067709 A102545
Adjacent sequences: A135566 A135567 A135568 this_sequence A135570 A135571 A135572
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KEYWORD
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easy,nonn,base
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AUTHOR
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Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Feb 23 2008, Mar 03 2008
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 03 2008
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