A026084 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) = 1. Also a(n) = T(n,n-1), where T is the array defined in A026082.

3, 13, 33, 98, 278, 804, 2320, 6723, 19515, 56769, 165421, 482793, 1411049, 4129323, 12098151, 35482857, 104169033, 306087111, 900134883, 2649106752, 7801834068, 22992061134, 67799076002, 200040038589, 590529542053, 1744148984223

Offset

4,1

Links

Table of n, a(n) for n=4..29.

Formula

Conjecture: (n+1)*a(n) +3*(-n+1)*a(n-1) +(-n-9)*a(n-2) +3*(n-5)*a(n-3)=0. - R. J. Mathar, Jun 23 2013

Crossrefs

First differences of A024998.

Sequence in context: A252979 A332366 A033943 * A211801 A016061 A154154

Adjacent sequences: A026081 A026082 A026083 * A026085 A026086 A026087

Keyword

nonn

Author

Clark Kimberling

Status

approved