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%I #6 Oct 19 2017 03:14:15
%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
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