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%I #5 Feb 22 2013 14:40:39
%S 0,1,4,8,17,35,66,124,229,414,742,1318,2320,4059,7062,12224,21071,
%T 36185,61930,105678,179847,305326,517212,874380,1475472,2485573,
%U 4180648,7021544,11777117,19728911,33011202
%N a(n) = A215082(2*n)
%F a(n) = a(n-1) + 2*a(n-2) + a(n-3) - 2*a(n-4) - 3*a(n-5) -a(n-6), a(0) = 0, a(1) = 1, a(2) = 4, a(3) = 8, a(4) = 17, a(5) = 35 .
%F G.f.: x*(x+1)*(2x+1)/((x^2+x+1)*(x^2+x-1)^2)
%Y Cf. A000045, A023607
%K nonn,easy
%O 0,3
%A _Philippe Deléham_, Aug 03 2012