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A083015 a(n) = the number of ordered pairs of n-bit bit strings, such that both bit strings have at least n/2 one-bits, or both have at most n/2 one-bits. 0
1, 2, 14, 32, 206, 512, 3128, 8192, 48238, 131072, 750584, 2097152, 11746424, 33554432, 184558304, 536870912, 2908113518, 8589934592, 45923227448, 137438953472, 726419131576, 2199023255552, 11506072128224, 35184372088832 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..23.

FORMULA

a(n) = 4^n/2 + 2^n*c - c^2/2; where c is (n choose n/2) for even n, 0 for odd n.

EXAMPLE

a(2)=14 because of the 16 ordered pairs, only (00,11) and (11,00) do not qualify.

CROSSREFS

Sequence in context: A231050 A337338 A322074 * A282036 A050591 A073535

Adjacent sequences:  A083012 A083013 A083014 * A083016 A083017 A083018

KEYWORD

nonn

AUTHOR

Jon Perry, May 31 2003

EXTENSIONS

Edited by Don Reble, Nov 07 2005

STATUS

approved

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Last modified September 26 11:08 EDT 2021. Contains 347665 sequences. (Running on oeis4.)