Number of ternary strings of length n avoiding the substrings 00, 11, 22, 121, 212, 202.

Terms

a(0) =1a(1) =3a(2) =6a(3) =9a(4) =14a(5) =23a(6) =36a(7) =57a(8) =90a(9) =143a(10) =226a(11) =357a(12) =566a(13) =895a(14) =1416a(15) =2241a(16) =3546a(17) =5611a(18) =8878a(19) =14049a(20) =22230a(21) =35175a(22) =55660a(23) =88073a(24) =139362a(25) =220519a(26) =348938a(27) =552141a(28) =873678a(29) =1382463