a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A026082.
A026085
a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A026082.
Terms
- a(0) =4a(1) =8a(2) =27a(3) =76a(4) =226a(5) =660a(6) =1939a(7) =5688a(8) =16704a(9) =49072a(10) =144254a(11) =424296a(12) =1248728a(13) =3677184a(14) =10834416a(15) =31939584a(16) =94205772a(17) =277997400a(18) =820747275a(19) =2424232956a(20) =7163519202a(21) =21176638868a(22) =62626464319a(23) =185276853192a(24) =548326714720
External references
- oeis: A026085