%I #16 May 02 2019 16:18:07
%S 1,2,3,18,180,1296,8100,50544,297432,1679616,9722592,58576608,
%T 358108128,2179768320,13162730688,78976384128,472093588224,
%U 2821109907456,16891882995456,101356447675392,608764662139392,3656158440062976,21947538146863104,131685972252346368
%N Number of strings of length n over Z_6 with trace 2 and subtrace 0.
%C Same as the number of strings of length n over Z_6 with trace 4 and subtrace 0.
%H Max Alekseyev, <a href="http://home.gwu.edu/~maxal/gpscripts/">PARI/GP scripts for miscellaneous math problems</a>
%H F. Ruskey <a href="http://combos.org/TSstringZ6">Strings over Z_6 with given trace and subtrace</a>
%F a(n; t, s) = a(n-1; t, s) + a(n-1; t+5, s+5t+1) + a(n-1; t+4, s+4t+4) + a(n-1; t+3, s+3t+3) + a(n-1; t+2, s+2t+2) + a(n-1; t+1, s+t+1) where t is the trace and s is the subtrace.
%Y Cf. A073971, A073972, A073973, A073974, A073975, A073976, A073977, A073978, A073979, A073980, A073981, A073982, A073984, A073985, A073986, A073987, A073988, A073989, A073990, A073991, A073992, A073993, A073994.
%K easy,nonn
%O 1,2
%A _Frank Ruskey_ and Nate Kube, Aug 16 2002
%E Terms a(11) onward from _Max Alekseyev_, Apr 09 2013