Search: id:A001444
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%I A001444
%S A001444 1,2,6,15,45,126,378,1107,3321,9882,29646,88695,266085,
%T A001444 797526,2392578,7175547,21526641,64573362,193720086,581140575,
%U A001444 1743421725,5230206126,15690618378,47071677987,141215033961
%N A001444 Bending a piece of wire of length n+1 (configurations that can only be 
               brought into coincidence by turning the figure over are counted as 
               different).
%C A001444 The wire stays in the plane, there are n bends, each is R,L or O.
%D A001444 Todd Andrew Simpson, ``Combinatorial Proofs and Generalizations of Weyl's 
               Denominator Formula,'' Ph. D. Dissertation, Penn State University, 
               1994.
%H A001444 <a href="Sindx_Fo.html#fold">Index entries for sequences obtained by 
               enumerating foldings</a>
%F A001444 (3^n + 3^[ n/2 ] )/2.
%e A001444 There are 2 ways to bend a piece of wire of length 2 (bend it or not).
%p A001444 f := n->(3^floor(n/2)+3^n)/2;
%Y A001444 Cf. A001997, A001998.
%Y A001444 Sequence in context: A148439 A151515 A052870 this_sequence A138574 A045628 
               A127383
%Y A001444 Adjacent sequences: A001441 A001442 A001443 this_sequence A001445 A001446 
               A001447
%K A001444 nonn,nice,easy
%O A001444 0,2
%A A001444 todo(AT)tasimpson.com (Todd Andrew Simpson)
%E A001444 Interpretation in terms of bending wire from Colin Mallows (colinm(AT)research.avayalabs.com).

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