a(n) = number of (s(0),s(1),...,s(n)) such that every s(i) is a nonnegative integer, s(0) = 1, s(n) = 5, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-4), where T is the array in A026120.

A026126

a(n) = number of (s(0),s(1),...,s(n)) such that every s(i) is a nonnegative integer, s(0) = 1, s(n) = 5, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-4), where T is the array in A026120.

Terms

    a(0) =1a(1) =4a(2) =16a(3) =56a(4) =188a(5) =608a(6) =1922a(7) =5972a(8) =18326a(9) =55704a(10) =168090a(11) =504348a(12) =1506531a(13) =4484208a(14) =13309572a(15) =39414568a(16) =116508361a(17) =343890196a(18) =1013840836a(19) =2986129168a(20) =8788591801a(21) =25850576024a(22) =76000747820a(23) =223361900840a(24) =656270632875

External references