%I A027561
%S A027561 0,0,0,0,0,2,6,22,56,152,356,858,1914,4334,9372,20440,43280,92114,
%T A027561 192182,402246,830328,1717496,3517668,7214218,14689994,29938526,
%U A027561 60697148,123127224,248807472,502963778,1013829414,2044098166
%N A027561 Number of 4-unbalanced strings of length n (=2^n-A027559[ n ]).
%F A027561 For n>0, a(n) = 2*Fibonacci(n+3) + 2^n + [5(-1)^n - 19]*3^[n/2-1]. - 
               R. Stephan, May 13 2004
%Y A027561 Sequence in context: A085286 A062085 A147800 this_sequence A126171 A002839 
               A109194
%Y A027561 Adjacent sequences: A027558 A027559 A027560 this_sequence A027562 A027563 
               A027564
%K A027561 nonn
%O A027561 0,6
%A A027561 R. K. Guy (rkg(AT)cpsc.ucalgary.ca), callan(AT)bayes.stat.wisc.edu (David 
               Callan)