login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

%I

%S 1,2,14,32,206,512,3128,8192,48238,131072,750584,2097152,11746424,

%T 33554432,184558304,536870912,2908113518,8589934592,45923227448,

%U 137438953472,726419131576,2199023255552,11506072128224,35184372088832

%N 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.

%F 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.

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

%K nonn

%O 0,2

%A _Jon Perry_, May 31 2003

%E Edited by _Don Reble_, Nov 07 2005

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 27 22:24 EDT 2021. Contains 348305 sequences. (Running on oeis4.)