a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0 = s(n), |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4. Also a(n) = T(n,n), where T is the array defined in A026082.
A026083
a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0 = s(n), |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4. Also a(n) = T(n,n), where T is the array defined in A026082.
Terms
- a(0) =6a(1) =12a(2) =38a(3) =104a(4) =300a(5) =856a(6) =2464a(7) =7104a(8) =20550a(9) =59580a(10) =173118a(11) =503960a(12) =1469546a(13) =4291644a(14) =12550290a(15) =36746592a(16) =107712306a(17) =316050372a(18) =928224594a(19) =2728494360a(20) =8026707864a(21) =23630376000a(22) =69614498268a(23) =205212650272a(24) =605292727450
External references
- oeis: A026083