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A143960 a(n) = the n-th positive integer with exactly n zeros and n ones in its binary representation. 1
2, 10, 38, 142, 542, 2110, 8318, 33022, 131582, 525310, 2099198, 8392702, 33562622, 134234110, 536903678, 2147549182, 8590065662, 34360000510, 137439477758, 549756862462, 2199025352702, 8796097216510, 35184380477438, 140737505132542, 562949986975742 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..25.

FORMULA

a(n) = 2^(2n-1) + 2^n - 2.

G.f.: 2*x*(1-2*x-2*x^2)/((1-x)*(1-4*x)*(1-2*x)). a(n) = 2*A099393(n-1). [R. J. Mathar, Nov 03 2008; G.f. corrected by Georg Fischer, May 12 2019]

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.

CROSSREFS

Cf. A099393.

Sequence in context: A081956 A120278 A166898 * A122117 A322211 A120949

Adjacent sequences:  A143957 A143958 A143959 * A143961 A143962 A143963

KEYWORD

base,nonn

AUTHOR

Leroy Quet, Sep 05 2008

EXTENSIONS

More terms from R. J. Mathar, Nov 03 2008

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)