Search: id:A074092
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%I A074092
%S A074092 1,2,8,40,144,448,1280,3456,8960,22528,55296,133120,315392,737280,
%T A074092 1703936,3899392,8847360,19922944,44564480,99090432,219152384,
%U A074092 482344960,1056964608,2306867200,5016387584,10871635968,23488102400
%N A074092 Number of plane binary trees of size n+3 and contracted height n.
%H A074092 H. Bottomley & A. Karttunen, <a href="a073345.txt">Notes concerning diagonals 
               of the square arrays A073345 and A073346.</a>
%F A074092 a(0) = 1, a(1) = 2, a(n) = 2^(n-1)*(n+2)*(n-1) = (2^n)*(C(n, n-2)+C(n-1, 
               n-2)) = 2^n * A000096(n-1).
%p A074092 A074092 := n -> `if`((n < 2),n+1,2^(n-1)*(n+2)*(n-1));
%p A074092 A074092v2 := n -> `if`((n < 2),n+1,(2^n)*(binomial(n,n-2)+binomial(n-1,
               n-2)));
%Y A074092 a(n) = A073346(n+3, n).
%Y A074092 Sequence in context: A152458 A087971 A127919 this_sequence A003445 A071007 
               A027617
%Y A074092 Adjacent sequences: A074089 A074090 A074091 this_sequence A074093 A074094 
               A074095
%K A074092 nonn
%O A074092 0,2
%A A074092 Antti Karttunen Aug 19 2002

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