Search: id:A118891
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%I A118891
%S A118891 1,2,4,8,16,31,60,116,223,428,820,1569,3002,5744,10992,21039,40273,
%T A118891 77095,147588,282538,540881,1035440,1982194,3794602,7264164,13906079,
%U A118891 26620957,50961552,97557726,186758657,357519595,684414146,1310201570
%N A118891 Number of binary sequences of length n with no subsequence 01110.
%C A118891 This is a_4(n) in the Doroslovacki reference.
%H A118891 R. Doroslovacki, <a href="http://www.emis.de/journals/MV/9434/mv943407.ps">
               Binary sequences without 011...110 (k-1 1's) for fixed k</a>, Mat. 
               Vesnik 46 (1994), no. 3-4, 93-98.
%o A118891 (PARI) { a4(n) = 1 + sum(i=1,n, sum(j=0,n-i, sum(k=0,(n-i-j)\2, sum(l=0,
               (n-i-j-2*k)\4, binomial(i-1,j)*binomial(i-1-j,k)*binomial(i-1-j-2*k,
               l)*binomial(n-i-j-2*k-3*l+1,l+1))))) }
%Y A118891 Cf. A000045, A005251, A049864.
%Y A118891 Sequence in context: A106399 A007800 A102726 this_sequence A107066 A141019 
               A152718
%Y A118891 Adjacent sequences: A118888 A118889 A118890 this_sequence A118892 A118893 
               A118894
%K A118891 nonn
%O A118891 0,2
%A A118891 Max Alekseyev, Jun 26 2007
%E A118891 More terms from Max Alekseyev (maxale(AT)gmail.com), Sep 25 2009

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