Number of runs of 0's of odd length in all ternary words of length n.

Terms

a(0) =0a(1) =1a(2) =4a(3) =17a(4) =64a(5) =233a(6) =820a(7) =2825a(8) =9568a(9) =31985a(10) =105796a(11) =346913a(12) =1129312a(13) =3653657a(14) =11758132a(15) =37665881a(16) =120172096a(17) =382039649a(18) =1210689028a(19) =3825777329a(20) =12058462720a(21) =37918780361a(22) =118986517684a(23) =372650082857