%I A030518
%S A030518 0,2,8,52,248,1302,6448,32552,162448,813802,4067448,20345052,
%T A030518 101717448,508626302,2543092448,12715657552,63578092448
%N A030518 Number of walks of length n between two vertices on a icosahedron at 
               distance 2.
%F A030518 A030517(n)=2*A030517(n-1)+2*A030518(n-1)+5*A030517(n-2), A030518(n)=2*A030517(n-1)+2*A030518(n-1)+5*A030518(n\
               -2)
%F A030518 a(n)=5^n/12-(-1)^n/12-(sqrt(5))^(n+1)/20-(-sqrt(5))^(n+1)/20. a(n)=4a(n-1)+10a(n-2)-20a(n-3)-25a(n-4). 
               - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 03 2004
%Y A030518 Sequence in context: A013085 A059429 A018987 this_sequence A123188 A027329 
               A136794
%Y A030518 Adjacent sequences: A030515 A030516 A030517 this_sequence A030519 A030520 
               A030521
%K A030518 nonn
%O A030518 1,2
%A A030518 Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)