a(n) = number of (s(0), s(1), ..., s(2n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n, s(0) = 2, s(2n) = 6. Also a(n) = T(2n,n-2), where T is the array defined in A026009.

A026014

a(n) = number of (s(0), s(1), ..., s(2n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n, s(0) = 2, s(2n) = 6. Also a(n) = T(2n,n-2), where T is the array defined in A026009.

Terms

    a(0) =1a(1) =6a(2) =28a(3) =119a(4) =483a(5) =1911a(6) =7448a(7) =28764a(8) =110466a(9) =422807a(10) =1615152a(11) =6163885a(12) =23514855a(13) =89714835a(14) =342411120a(15) =1307613480a(16) =4997082510a(17) =19111589280a(18) =73154916744a(19) =280265589198

External references