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) = 0, s(2n) = n. Also a(n) = T(2n,n), where T is the array in A026300.

A026302

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) = 0, s(2n) = n. Also a(n) = T(2n,n), where T is the array in A026300.

Terms

    a(0) =1a(1) =2a(2) =9a(3) =44a(4) =230a(5) =1242a(6) =6853a(7) =38376a(8) =217242a(9) =1239980a(10) =7123765a(11) =41141916a(12) =238637282a(13) =1389206210a(14) =8112107475a(15) =47495492400a(16) =278722764954

External references