Number of (s(0), s(1), ..., s(2n)) such that 0 < s(i) < 9 and |s(i) - s(i-1)| = 1 for i = 1,2,...,2n, s(0) = 4, s(2n) = 4.

A094854

Number of (s(0), s(1), ..., s(2n)) such that 0 < s(i) < 9 and |s(i) - s(i-1)| = 1 for i = 1,2,...,2n, s(0) = 4, s(2n) = 4.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =20a(4) =69a(5) =241a(6) =846a(7) =2977a(8) =10490a(9) =36994a(10) =130532a(11) =460737a(12) =1626629a(13) =5743674a(14) =20283121a(15) =71632290a(16) =252989326a(17) =893528468a(18) =3155899165a(19) =11146628105a(20) =39370204614a(21) =139057473905a(22) =491159630010

External references