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A143960
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a(n) = the n-th positive integer with exactly n zeros and n ones in its binary representation.
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0
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2, 10, 38, 142, 542, 2110, 8318, 33022, 131582, 525310, 2099198, 8392702, 33562622, 134234110, 536903678, 2147549182, 8590065662, 34360000510, 137439477758, 549756862462, 2199025352702, 8796097216510, 35184380477438
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n) = 2^(2n-1) + 2^n - 2.
G.f.: 2x(1-2x+2x^2)/((1-x)(1-4x)(1-2x)). a(n)=2*A099393(n-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 03 2008]
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EXAMPLE
| The first of the (10) positive integers with exactly three 0's and three 1's in their binary representation are 35 (100011 in binary), 37 (100101 in binary), 38 (100110 in binary), etc. a(3) is the third of these, which is 38.
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CROSSREFS
| Sequence in context: A081956 A120278 A166898 * A122117 A120949 A186097
Adjacent sequences: A143957 A143958 A143959 * A143961 A143962 A143963
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KEYWORD
| base,nonn
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AUTHOR
| Leroy Quet Sep 05 2008
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 03 2008
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