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%I #16 May 02 2019 16:16:22
%S 0,4,18,48,180,1080,7056,44928,286416,1762560,10349856,60217344,
%T 356638464,2145709440,12976433280,78399995904,472093588224,
%U 2832561529344,16960580969472,101554796888064,608733733690368,3652526115938304,21926115464435712,131620960833896448
%N Number of strings of length n over Z_6 with trace 3 and subtrace 2.
%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, A073983, A073984, A073985, A073986, A073987, A073988, A073989, A073990, 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