a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 2, s(n) = 5. Also a(n) = T(n,n-3), where T is the array in A026323.

A026328

a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 2, s(n) = 5. Also a(n) = T(n,n-3), where T is the array in A026323.

Terms

    a(0) =1a(1) =4a(2) =15a(3) =50a(4) =161a(5) =504a(6) =1553a(7) =4730a(8) =14289a(9) =42900a(10) =128193a(11) =381654a(12) =1132950a(13) =3355392a(14) =9918990a(15) =29278012a(16) =86316259a(17) =254227980a(18) =748200145a(19) =2200619806a(20) =6469372932a(21) =19011518480a(22) =55853259800a(23) =164055406320a(24) =481804384035

External references