Search: id:A141447
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%I A141447
%S A141447 0,1,2,6,12,28,56,120,240,496,992,2016,4032,8128,16256,32640,65280,
%T A141447 130816,261632,523776,1047552,2096128,4192256,8386560,16773120
%N A141447 Number of n-bead black-white reversible strings; also binary grids; string 
               is not palindromic.
%C A141447 a(n)=A005418(n+1)-A016116(n+2) analogue of A006516(n)=A007582(n)-A000079(n)
%C A141447 a(n) is also the number of induced subgraphs with odd number of edges 
               in the path graph P(n), with a(1)=0, a(2)=1,... [From Alessandro 
               Cosentino (cosenal(AT)gmail.com), Feb 06 2009]
%F A141447 2^(n-1) - 2^[(n-1)/2] a(n+4)=6a(n+2)-8a(n), n=1,2,3,... a(1)=0, a(2)=1, 
               a(3)=2, a(4)=6
%F A141447 a(n)=A122746(n-1), n>0. O.g.f.: x/((1-2x)(1-2x^2)). [From R. J. Mathar 
               (mathar(AT)strw.leidenuniv.nl), Aug 27 2008]
%F A141447 a(n+1) = A077957(n) + 2*a(n) with a(1)=0. a(n+2) = A000079(n+1) + 2*a(n) 
               with a(1)=0 a(2)=1. - Yosu Yurramendi (yosu.yurramendi(AT)ehu.es), 
               Aug 10 2008
%e A141447 a(11)=2^(11-1) - 2^[(11-1)/2] = 2^10 - 2^5 = 1024-32 =992
%Y A141447 Cf. A005418, A016116.
%Y A141447 Sequence in context: A112510 A011949 A089820 this_sequence A122746 A057582 
               A094779
%Y A141447 Adjacent sequences: A141444 A141445 A141446 this_sequence A141448 A141449 
               A141450
%K A141447 nonn
%O A141447 1,3
%A A141447 Yosu Yurramendi (yosu.yurramendi(AT)ehu.es), Aug 07 2008

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