a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, s(n) = 4, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-4), where T is the array defined in A026105.
A026110
a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, s(n) = 4, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-4), where T is the array defined in A026105.
Terms
- a(0) =1a(1) =4a(2) =15a(3) =50a(4) =160a(5) =496a(6) =1509a(7) =4530a(8) =13475a(9) =39820a(10) =117117a(11) =343278a(12) =1003665a(13) =2929200a(14) =8537910a(15) =24863724a(16) =72363951a(17) =210532540a(18) =612398025a(19) =1781252110a(20) =5181318054a(21) =15073505216a(22) =43860668800a(23) =127657036000a(24) =371654416575
External references
- oeis: A026110