Number of length-6 0..n arrays with no adjacent pair x,x+1 repeated.

Terms

a(0) =42a(1) =626a(2) =3816a(3) =15036a(4) =45590a(5) =115902a(6) =259476a(7) =527576a(8) =994626a(9) =1764330a(10) =2976512a(11) =4814676a(12) =7514286a(13) =11371766a(14) =16754220a(15) =24109872a(16) =33979226a(17) =47006946a(18) =63954456a(19) =85713260a(20) =113318982a(21) =147966126a(22) =191023556a(23) =244050696a(24) =308814450a(25) =387306842