%I A120494
%S A120494 1,1,2,3,5,13,139,19136,366167031,134078294225149313,
%T A120494 17976988982325707481237962186849833,
%U A120494 323172132870659875927245721269598505772051876540063951439000722587455
%N A120494 A vector group determinant sequence in which the next element is made 
               by a sum of the older elements over a vector like 2 X 2 matrix group.
%C A120494 This sequence type gets very large very fast.
%F A120494 s[1] = {{1, 0}, {0, 1}}; s[2] = {{1, 0}, {0, -1}}; s[3] = {{0, 1}, {1, 
               0}}; s[4] = {{0, 1}, {-1, 0}}; a[0] = {0, 1, 1, 2}; a[1] = {1, 1, 
               2, 3}; a[n_] := a[n] = {a[n - 1][[2]], a[n - 1][[3]], a[n - 1][[4]], 
               Det[Sum[a[n - 1][[i]]*s[i], {i, 1, 4}]]} a(n)=a[n][[1]]
%t A120494 s[1] = {{1, 0}, {0, 1}}; s[2] = {{1, 0}, {0, -1}}; s[3] = {{0, 1}, {1, 
               0}}; s[4] = {{0, 1}, {-1, 0}}; a[0] = {0, 1, 1, 2}; a[1] = {1, 1, 
               2, 3}; a[n_] := a[n] = {a[n - 1][[2]], a[n - 1][[3]], a[n - 1][[4]], 
               Det[Sum[a[n - 1][[i]]*s[i], {i, 1, 4}]]} Table[a[n][[1]], {n, 1, 
               15}]
%Y A120494 Sequence in context: A005478 A117740 A041047 this_sequence A164825 A038601 
               A114747
%Y A120494 Adjacent sequences: A120491 A120492 A120493 this_sequence A120495 A120496 
               A120497
%K A120494 nonn,uned
%O A120494 0,3
%A A120494 Roger Bagula (rlbagulatftn(AT)yahoo.com), Aug 06 2006