Number of 0..4 arrays of length n with each element unequal to at least one neighbor, with new values introduced in 0..4 order.

A221455

Number of 0..4 arrays of length n with each element unequal to at least one neighbor, with new values introduced in 0..4 order.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =7a(4) =25a(5) =101a(6) =436a(7) =1971a(8) =9159a(9) =43262a(10) =206285a(11) =988963a(12) =4755888a(13) =22910979a(14) =110480787a(15) =533057462a(16) =2572761417a(17) =12419474751a(18) =59958562568a(19) =289483787719

External references