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%I #5 Mar 30 2012 18:39:23
%S 1,-2,4,16,-32,-128,-512,4096,-8192,-32768,-131072,1048576,4194304,
%T -33554432,268435456,4294967296,-8589934592,-34359738368,
%U -137438953472,1099511627776,4398046511104,-35184372088832,281474976710656
%N Determinant of n X n partial Hadamard matrix with coefficient m(i,j) 1<=i,j<=n (see comment).
%C Let M(infinity) be the infinite matrix with coefficient m(i,j) i>=1, j>=1 defined as follows : M(0)=1 and M(k) is the 2^k X 2^k matrix following the recursion : +M(k-1)-M(k-1) M(k)= -M(k-1)-M(k-1)
%F It appears that abs(a(n))=2^A000788(n). What is the rule for signs? Does sum(k=1, n, a(k+1)/a(k))=0 iff n is in A073536 ?
%e M(2)=/1,-1/-1,-1/ then a(2)=detM(2)=-2
%K sign
%O 1,2
%A _Benoit Cloitre_, Jun 03 2004
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